diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 627de584..40b2f662 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -425,6 +425,7 @@ phutil_register_library_map(array(
     'ArcanistVariableVariableXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistVariableVariableXHPASTLinterRule.php',
     'ArcanistVariableVariableXHPASTLinterRuleTestCase' => 'lint/linter/xhpast/rules/__tests__/ArcanistVariableVariableXHPASTLinterRuleTestCase.php',
     'ArcanistVersionWorkflow' => 'workflow/ArcanistVersionWorkflow.php',
+    'ArcanistWeldWorkflow' => 'workflow/ArcanistWeldWorkflow.php',
     'ArcanistWhichWorkflow' => 'workflow/ArcanistWhichWorkflow.php',
     'ArcanistWorkflow' => 'workflow/ArcanistWorkflow.php',
     'ArcanistWorkingCopyIdentity' => 'workingcopyidentity/ArcanistWorkingCopyIdentity.php',
@@ -872,6 +873,7 @@ phutil_register_library_map(array(
     'ArcanistVariableVariableXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistVariableVariableXHPASTLinterRuleTestCase' => 'ArcanistXHPASTLinterRuleTestCase',
     'ArcanistVersionWorkflow' => 'ArcanistWorkflow',
+    'ArcanistWeldWorkflow' => 'ArcanistWorkflow',
     'ArcanistWhichWorkflow' => 'ArcanistWorkflow',
     'ArcanistWorkflow' => 'Phobject',
     'ArcanistWorkingCopyIdentity' => 'Phobject',
diff --git a/src/repository/parser/ArcanistMercurialParser.php b/src/repository/parser/ArcanistMercurialParser.php
index 8317cc7c..4eb10e2f 100644
--- a/src/repository/parser/ArcanistMercurialParser.php
+++ b/src/repository/parser/ArcanistMercurialParser.php
@@ -174,6 +174,10 @@ final class ArcanistMercurialParser extends Phobject {
           case 'bookmark':
             $commit['bookmark'] = $value;
             break;
+          case 'obsolete':
+            // This is an extra field added by the "evolve" extension even
+            // if HGPLAIN=1 is set. See PHI502.
+            break;
           default:
             throw new Exception(
               pht("Unknown Mercurial log field '%s'!", $name));
diff --git a/src/unit/parser/ArcanistGoTestResultParser.php b/src/unit/parser/ArcanistGoTestResultParser.php
index ce6451f5..92a9c9ae 100644
--- a/src/unit/parser/ArcanistGoTestResultParser.php
+++ b/src/unit/parser/ArcanistGoTestResultParser.php
@@ -68,7 +68,7 @@ final class ArcanistGoTestResultParser extends ArcanistTestResultParser {
       if (strncmp($line, 'ok', 2) === 0) {
         $meta = array();
         preg_match(
-          '/^ok[\s\t]+(?P<test_name>\w.*)[\s\t]+(?P<time>.*)s.*/',
+          '/^ok[\s]+(?P<test_name>\w.*)[\s]+(?:(?P<time>.*)s|\(cached\))/',
           $line,
           $meta);
 
@@ -84,7 +84,10 @@ final class ArcanistGoTestResultParser extends ArcanistTestResultParser {
           $result = new ArcanistUnitTestResult();
           $result->setName($test_name);
           $result->setResult(ArcanistUnitTestResult::RESULT_PASS);
-          $result->setDuration((float)$meta['time']);
+
+          if (array_key_exists('time', $meta)) {
+            $result->setDuration((float)$meta['time']);
+          }
 
           $results[] = $result;
         } else {
diff --git a/src/unit/parser/__tests__/ArcanistGoTestResultParserTestCase.php b/src/unit/parser/__tests__/ArcanistGoTestResultParserTestCase.php
index cf6cf5ed..923787ee 100644
--- a/src/unit/parser/__tests__/ArcanistGoTestResultParserTestCase.php
+++ b/src/unit/parser/__tests__/ArcanistGoTestResultParserTestCase.php
@@ -103,6 +103,27 @@ final class ArcanistGoTestResultParserTestCase extends PhutilTestCase {
     }
   }
 
+  public function testNonVerboseOutputV110() {
+    $stubbed_results = Filesystem::readFile(
+      dirname(__FILE__).'/testresults/go.nonverbose-go1.10');
+
+    $parsed_results = id(new ArcanistGoTestResultParser())
+      ->parseTestResults('package', $stubbed_results);
+
+    $this->assertEqual(2, count($parsed_results));
+    $this->assertEqual(
+      'Go::TestCase::package::subpackage1',
+      $parsed_results[0]->getName());
+    $this->assertEqual(
+      'Go::TestCase::package::subpackage2',
+      $parsed_results[1]->getName());
+    foreach ($parsed_results as $result) {
+      $this->assertEqual(
+        ArcanistUnitTestResult::RESULT_PASS,
+        $result->getResult());
+    }
+  }
+
   public function testSingleTestCaseSuccessfulGo14() {
     $stubbed_results = Filesystem::readFile(
       dirname(__FILE__).'/testresults/go.single-test-case-successful-go1.4');
diff --git a/src/unit/parser/__tests__/testresults/go.nonverbose-go1.10 b/src/unit/parser/__tests__/testresults/go.nonverbose-go1.10
new file mode 100644
index 00000000..e23664cb
--- /dev/null
+++ b/src/unit/parser/__tests__/testresults/go.nonverbose-go1.10
@@ -0,0 +1,2 @@
+ok  	package/subpackage1	(cached)
+ok  	package/subpackage2	0.010s
diff --git a/src/workflow/ArcanistFeatureWorkflow.php b/src/workflow/ArcanistFeatureWorkflow.php
index 8e82aec1..53d5772f 100644
--- a/src/workflow/ArcanistFeatureWorkflow.php
+++ b/src/workflow/ArcanistFeatureWorkflow.php
@@ -171,7 +171,7 @@ EOTEXT
     }
 
     echo $stdout;
-    fprintf(STDERR, $stderr);
+    fprintf(STDERR, '%s', $stderr);
     return $err;
   }
 
diff --git a/src/workflow/ArcanistLintWorkflow.php b/src/workflow/ArcanistLintWorkflow.php
index 75d0667f..9ab1aca2 100644
--- a/src/workflow/ArcanistLintWorkflow.php
+++ b/src/workflow/ArcanistLintWorkflow.php
@@ -110,7 +110,9 @@ EOTEXT
           'patches suggested by lint without prompting.'),
       ),
       'everything' => array(
-        'help' => pht('Lint all files in the project.'),
+        'help' => pht(
+          'Lint all tracked files in the working copy. Ignored files and '.
+          'untracked files will not be linted.'),
         'conflicts' => array(
           'rev' => pht('%s lints all files', '--everything'),
         ),
@@ -155,7 +157,8 @@ EOTEXT
     if ($everything && $paths) {
       throw new ArcanistUsageException(
         pht(
-          'You can not specify paths with %s. The %s flag lints every file.',
+          'You can not specify paths with %s. The %s flag lints every '.
+          'tracked file in the working copy.',
           '--everything',
           '--everything'));
     }
diff --git a/src/workflow/ArcanistUnitWorkflow.php b/src/workflow/ArcanistUnitWorkflow.php
index 00ef8a59..c0a2fabc 100644
--- a/src/workflow/ArcanistUnitWorkflow.php
+++ b/src/workflow/ArcanistUnitWorkflow.php
@@ -91,7 +91,9 @@ EOTEXT
           'Harbormaster build target.'),
       ),
       'everything' => array(
-        'help' => pht('Run every test.'),
+        'help' => pht(
+          'Run every test associated with a tracked file in the working '.
+          'copy.'),
         'conflicts' => array(
           'rev' => pht('%s runs all tests.', '--everything'),
         ),
@@ -134,7 +136,8 @@ EOTEXT
     if ($everything && $paths) {
       throw new ArcanistUsageException(
         pht(
-          'You can not specify paths with %s. The %s flag runs every test.',
+          'You can not specify paths with %s. The %s flag runs every test '.
+          'associated with a tracked file in the working copy.',
           '--everything',
           '--everything'));
     }
diff --git a/src/workflow/ArcanistWeldWorkflow.php b/src/workflow/ArcanistWeldWorkflow.php
new file mode 100644
index 00000000..7034db54
--- /dev/null
+++ b/src/workflow/ArcanistWeldWorkflow.php
@@ -0,0 +1,133 @@
+<?php
+
+final class ArcanistWeldWorkflow extends ArcanistWorkflow {
+
+  public function getWorkflowName() {
+    return 'weld';
+  }
+
+  public function getCommandSynopses() {
+    return phutil_console_format(<<<EOTEXT
+      **weld** [options] __file__ __file__ ...
+EOTEXT
+      );
+  }
+
+  public function getCommandHelp() {
+    return phutil_console_format(<<<EOTEXT
+          Robustly fuse two or more files together. The resulting joint is
+          much stronger than the one created by tools like __cat__.
+EOTEXT
+      );
+  }
+
+  public function getArguments() {
+    return array(
+      '*' => 'files',
+    );
+  }
+
+  public function run() {
+    $files = $this->getArgument('files');
+    if (count($files) < 2) {
+      throw new ArcanistUsageException(
+        pht('Specify two or more files to weld together.'));
+    }
+
+    $buffer = array();
+    foreach ($files as $file) {
+      $data = Filesystem::readFile($file);
+      if (!strlen($data)) {
+        continue;
+      }
+      $lines = phutil_split_lines($data, true);
+
+      $overlap = mt_rand(16, 32);
+
+      if (count($buffer) > 6) {
+        $overlap = min($overlap, ceil(count($buffer) / 2));
+      }
+
+      if (count($lines) > 6) {
+        $overlap = min($overlap, ceil(count($lines) / 2));
+      }
+
+      $overlap = min($overlap, count($buffer));
+      $overlap = min($overlap, count($lines));
+
+      $buffer_len = count($buffer);
+      for ($ii = 0; $ii < $overlap; $ii++) {
+        $buffer[$buffer_len - $overlap + $ii] = $this->weldLines(
+          $buffer[$buffer_len - $overlap + $ii],
+          $lines[$ii],
+          ($ii + 0.5) / $overlap);
+      }
+
+      for ($ii = $overlap; $ii < count($lines); $ii++) {
+        $buffer[] = $lines[$ii];
+      }
+    }
+
+    echo implode('', $buffer);
+  }
+
+  private function weldLines($u, $v, $bias) {
+    $newline = null;
+    $matches = null;
+
+    if (preg_match('/([\r\n]+)\z/', $u, $matches)) {
+      $newline = $matches[1];
+    }
+
+    if (preg_match('/([\r\n]+)\z/', $v, $matches)) {
+      $newline = $matches[1];
+    }
+
+    $u = rtrim($u, "\r\n");
+    $v = rtrim($v, "\r\n");
+
+    $u = phutil_utf8v_combined($u);
+    $v = phutil_utf8v_combined($v);
+
+    $len = max(count($u), count($v));
+
+    while (count($u) < $len) {
+      $u[] = ' ';
+    }
+    while (count($v) < $len) {
+      $v[] = ' ';
+    }
+
+    $rand_max = mt_getrandmax();
+
+    $result = array();
+    for ($ii = 0; $ii < $len; $ii++) {
+      $uc = $u[$ii];
+      $vc = $v[$ii];
+
+      $threshold = $bias;
+      if ($uc == ' ') {
+        $threshold = 1;
+      }
+
+      if ($vc == ' ') {
+        $threshold = 0;
+      }
+
+      if ((mt_rand() / $rand_max) > $threshold) {
+        $r = $uc;
+      } else {
+        $r = $vc;
+      }
+
+      $result[] = $r;
+    }
+
+    if ($newline !== null) {
+      $result[] = $newline;
+    }
+
+    return implode('', $result);
+  }
+
+}