git_cl sanity checks

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index 21ade2a28e9987cfdc76425e64f8f0f027b6b1e6..655a2bafcae3e880aa852264799526fdb70d8148 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -163,6 +163,32 @@ def is_dirty_git_tree(cmd):
     return True
   return False
 
+
+def git_cl_sanity_checks(upstream_git_obj):
+  # First verify that the commit we're diffing against is in our tree.
+  upstream_sha = RunGit(['rev-parse', '--verify', upstream_git_obj]).strip()
+  common_ancestor = RunGit(['merge-base', upstream_sha, 'HEAD']).strip()
+  if upstream_sha != common_ancestor:

[M-A Ruel, 2012/10/27 01:29:41]

I disagree with this check. It happens I git fetch but do not rebase, simply
because I rebased for one of the CL I'm working on but not another one.

[Isaac (away), 2012/10/27 01:32:55]

This is intended to catch diffing against a rebased branch while your current
branch is not rebased.  That means the diff will pull in diff from lots of other
commits.

I'm not clear why your scenario would trigger this -- can you clarify?

[M-A Ruel, 2012/10/27 01:37:23]

git checkout -b work origin/master
vim foo
git commit -a -m "Rock on"
git checkout -b leisure origin/master
git pull
# Assumes something was pulled.
git checkout work
git cl upload
# Note upstream == origin/master, but "ref-parse origin/master" != "merge-base
origin/master HEAD"

+    print >> sys.stderr, (
+        'ERROR: %s is not in the current branch.  You may need to rebase your '
+        'tracking branch' % upstream_sha)
+    return False
+
+  commits_in_diff = RunGit(
+      ['rev-list', '^%s' % upstream_sha, 'HEAD']).splitlines()
+  commits_in_origin = RunGit(
+      ['rev-list', '^%s' % upstream_sha, 'remotes/origin/master']).splitlines()
+
+  common_commits = set(commits_in_diff) & set(commits_in_origin)
+  if common_commits:
+    print >> sys.stderr, (
+        'ERROR: Your diff contains %d commits already in origin/master.\n'
+        'Run "git log --oneline origin/master..HEAD" to get a list of commits '
+        'in the diff' % len(common_commits))
+    return False
+  return True
+
+
 def MatchSvnGlob(url, base_url, glob_spec, allow_wildcards):
   """Return the corresponding git ref if |base_url| together with |glob_spec|
   matches the full |url|.
@@ -607,6 +633,9 @@ or verify this branch is set up to track another (via the --track argument to
     self.has_issue = False
 
   def GetChange(self, upstream_branch, author):
+    if not git_cl_sanity_checks(upstream_branch):
+      DieWithError('\nGit sanity check failure')
+
     root = RunCommand(['git', 'rev-parse', '--show-cdup']).strip() or '.'
     absroot = os.path.abspath(root)