Fix principal error in makeChangesWithContext()

Summary: `array_fill()`, contrary to `range()`, doesn't accept the last element but the number of elements.

Test Plan: Reparsed commit not changed after the last diff but rebased which was previously reported as changed.

Reviewers: jungejason, epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D2783

src/applications/differential/storage/DifferentialChangeset.php

@@ -142,7 +142,7 @@ final class DifferentialChangeset extends DifferentialDAO {
       $changes = explode("\n", $hunk->getChanges());
       foreach ($changes as $l => $line) {
         if ($line[0] == '+' || $line[0] == '-') {
-          $context += array_fill($l - $num_lines, $l + $num_lines, true);
+          $context += array_fill($l - $num_lines, 2 * $num_lines + 1, true);
         }
       }
       $with_context[] = array_intersect_key($changes, $context);