Shorten extremely long credential names when migrating them

Summary: Fixes T4183. If you have too many repositories sharing the same credential and MySQL is in strict mode, we'll fail a query when trying to write a credential with a name longer than 255 characters. Instead, shorten the variable-length part to 128 characters.

Test Plan: Wiped credentials column and successfully re-ran migration with `storage upgrade --force --apply phabricator:20131121.repocredentials.2.mig.php`

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4183

Differential Revision: https://secure.phabricator.com/D7677

resources/sql/patches/20131121.repocredentials.2.mig.php

@@ -69,7 +69,7 @@ foreach ($map as $credential_type => $credential_usernames) {
       $callsigns = mpull($repositories, 'getCallsign');
       $name = pht(
         'Migrated Repository Credential (%s)',
-        implode(', ', $callsigns));
+        phutil_utf8_shorten(implode(', ', $callsigns), 128));
 
       echo "Creating: {$name}...\n";