Make udiff print reasonable errors while not on a branch.

git_upstream_diff.py

Index: git_upstream_diff.py
diff --git a/git_upstream_diff.py b/git_upstream_diff.py
index c7fe1f3449cad367d2d629ed24237bb99589dc2a..d8071e34f23913510e027d32270102292dbaee52 100755
--- a/git_upstream_diff.py
+++ b/git_upstream_diff.py
@@ -9,7 +9,7 @@ import sys
 import subprocess2
 
 from git_common import current_branch, get_or_create_merge_base, config_list

[agable, 2014/03/26 15:36:24]

Would be good to sort these imports.

[iannucci, 2014/03/26 18:51:11]

Done.

-from git_common import GIT_EXE
+from git_common import GIT_EXE, upstream
 
 def main(args):
   default_args = config_list('depot-tools.upstream-diff.default-args')
@@ -22,10 +22,20 @@ def main(args):
                         'instead of line-wise diff'))
   opts, extra_args = parser.parse_known_args(args)
 
+  cur = current_branch()
+  if not cur or cur == 'HEAD':
+    print 'fatal: cannot perform git-upstream-diff while not on a branch'
+    return 1
+
+  par = upstream(cur)
+  if not par:
+    print 'fatal: branch %s has no configured upstream' % cur

[agable, 2014/03/26 15:36:24]

fatal: branch.%s.merge is not configured
?

[iannucci, 2014/03/26 18:51:11]

Yeah, but it's also ...remote. I'm changing to the standard git error message.

+    return 1
+
   cmd = [GIT_EXE, 'diff', '--patience', '-C', '-C']
   if opts.wordwise:
     cmd += ['--word-diff=color', r'--word-diff-regex=(\w+|[^[:space:]])']
-  cmd += [get_or_create_merge_base(current_branch())]
+  cmd += [get_or_create_merge_base(cur, par)]
 
   cmd += extra_args