bot_update: set the push URL to the actual remote, not the cache.

Bug: 876734
Change-Id: I5741b526f14d79f7a8eb42808c1eef93434739cb
Reviewed-on: https://chromium-review.googlesource.com/1187368
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>

recipes/recipe_modules/bot_update/resources/bot_update.py

@@ -715,6 +715,7 @@ def _git_checkout(sln, sln_dir, revisions, refs, git_cache_dir, cleanup_dir):
         _git_disable_gc(sln_dir)
         git('remote', 'set-url', 'origin', mirror_dir, cwd=sln_dir)
         git('fetch', 'origin', cwd=sln_dir)
+      git('remote', 'set-url', '--push', 'origin', url, cwd=sln_dir)
       for ref in refs:
         refspec = '%s:%s' % (ref, ref.lstrip('+'))
         git('fetch', 'origin', refspec, cwd=sln_dir)