[StGit PATCH 6/6] Handle failed pushes differently depending on cause

["Karl Hasselström" <kha@treskal.com>]

Specifically, if the push failed because of a merge conflict, the
patch should be applied but empty; and if it fails for any other
reason (such as a too-dirty worktree), the patch should not be
applied.

This fixes the data loss bug tested for by t3000.

Signed-off-by: Karl Hasselström <kha@treskal.com>

---

 stgit/lib/git.py         |   21 ++++++++++++++-------
 stgit/lib/transaction.py |    4 +++-
 t/t3000-dirty-merge.sh   |    2 +-
 3 files changed, 18 insertions(+), 9 deletions(-)


diff --git a/stgit/lib/git.py b/stgit/lib/git.py
index cdfe885..35b9bbf 100644
--- a/stgit/lib/git.py
+++ b/stgit/lib/git.py
@@ -433,6 +433,9 @@ class Repository(RunWithEnv):
 class MergeException(exception.StgException):
     pass
 
+class MergeConflictException(MergeException):
+    pass
+
 class Index(RunWithEnv):
     def __init__(self, repository, filename):
         self.__repository = repository
@@ -517,14 +520,18 @@ class IndexAndWorktree(RunWithEnv):
         assert isinstance(ours, Tree)
         assert isinstance(theirs, Tree)
         try:
-            self.run(['git', 'merge-recursive', base.sha1, '--', ours.sha1,
-                      theirs.sha1],
-                     env = { 'GITHEAD_%s' % base.sha1: 'ancestor',
-                             'GITHEAD_%s' % ours.sha1: 'current',
-                             'GITHEAD_%s' % theirs.sha1: 'patched'}
-                     ).cwd(self.__worktree.directory).discard_output()
+            r = self.run(['git', 'merge-recursive', base.sha1, '--', ours.sha1,
+                          theirs.sha1],
+                         env = { 'GITHEAD_%s' % base.sha1: 'ancestor',
+                                 'GITHEAD_%s' % ours.sha1: 'current',
+                                 'GITHEAD_%s' % theirs.sha1: 'patched'}
+                         ).cwd(self.__worktree.directory)
+            r.discard_output()
         except run.RunException, e:
-            raise MergeException('Index/worktree dirty')
+            if r.exitcode == 1:
+                raise MergeConflictException()
+            else:
+                raise MergeException('Index/worktree dirty')
     def changed_files(self):
         return self.run(['git', 'diff-files', '--name-only']).output_lines()
     def update_index(self, files):
diff --git a/stgit/lib/transaction.py b/stgit/lib/transaction.py
index 3613b15..2946a67 100644
--- a/stgit/lib/transaction.py
+++ b/stgit/lib/transaction.py
@@ -197,10 +197,12 @@ class StackTransaction(object):
                 tree = iw.index.write_tree()
                 self.__current_tree = tree
                 s = ' (modified)'
-            except git.MergeException:
+            except git.MergeConflictException:
                 tree = ours
                 merge_conflict = True
                 s = ' (conflict)'
+            except git.MergeException, e:
+                self.__halt(str(e))
         cd = cd.set_tree(tree)
         self.patches[pn] = self.__stack.repository.commit(cd)
         del self.unapplied[self.unapplied.index(pn)]
diff --git a/t/t3000-dirty-merge.sh b/t/t3000-dirty-merge.sh
index dd81c9e..d87bba1 100755
--- a/t/t3000-dirty-merge.sh
+++ b/t/t3000-dirty-merge.sh
@@ -22,7 +22,7 @@ test_expect_success 'Pop one patch and update the other' '
     stg refresh
 '
 
-test_expect_failure 'Push with dirty worktree' '
+test_expect_success 'Push with dirty worktree' '
     echo 4 > a &&
     [ "$(echo $(stg applied))" = "p1" ] &&
     [ "$(echo $(stg unapplied))" = "p2" ] &&