Don't "hang" gclient if fast-forward is not possible.

As noticed in the TODO, raw_input (used by ask_for_data) works badly
on background threads. On my Windows it doesn't even print the prompt which
makes it hard to interact with it.

Better to just abort and tell the user of gclient how to proceed.

BUG=

Review URL: https://chromiumcodereview.appspot.com/15421005

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@201295 0039d316-1c4b-4281-b951-d872f2087c98

gclient_scm.py

@@ -69,7 +69,11 @@ class GitDiffFilterer(DiffFiltererWrapper):
     return re.sub("[a|b]/" + self._current_file, self._replacement_file, line)
 
 
-def ask_for_data(prompt):
+def ask_for_data(prompt, options):
+  if options.jobs > 1:
+    raise gclient_utils.Error("Background task requires input. Rerun "
+                              "gclient with --jobs=1 so that\n"
+                              "interaction is possible.")
   try:
     return raw_input(prompt)
   except KeyboardInterrupt:
@@ -454,17 +458,16 @@ class GitWrapper(SCMWrapper):
           merge_args.append('--ff-only')
         merge_args.append(upstream_branch)
         merge_output = scm.GIT.Capture(merge_args, cwd=self.checkout_path)
-      except subprocess2.CalledProcessError, e:
+      except subprocess2.CalledProcessError as e:
         if re.match('fatal: Not possible to fast-forward, aborting.', e.stderr):
           if not printed_path:
             print('\n_____ %s%s' % (self.relpath, rev_str))
             printed_path = True
           while True:
             try:
-              # TODO(maruel): That can't work with --jobs.
               action = ask_for_data(
                   'Cannot fast-forward merge, attempt to rebase? '
-                  '(y)es / (q)uit / (s)kip : ')
+                  '(y)es / (q)uit / (s)kip : ', options)
             except ValueError:
               raise gclient_utils.Error('Invalid Character')
             if re.match(r'yes|y', action, re.I):
@@ -755,7 +758,7 @@ class GitWrapper(SCMWrapper):
               'Cannot rebase because of unstaged changes.\n'
               '\'git reset --hard HEAD\' ?\n'
               'WARNING: destroys any uncommitted work in your current branch!'
-              ' (y)es / (q)uit / (s)how : ')
+              ' (y)es / (q)uit / (s)how : ', options)
           if re.match(r'yes|y', rebase_action, re.I):
             self._Run(['reset', '--hard', 'HEAD'], options)
             # Should this be recursive?

tests/gclient_scm_test.py

@@ -684,6 +684,7 @@ class BaseGitWrapperTestCase(GCBaseTestCase, StdoutCheck, TestCaseUtils,
       self.reset = False
       self.nohooks = False
       self.merge = False
+      self.jobs = 1
       self.delete_unversioned_trees = False
 
   sample_git_import = """blob