[StGit PATCH 2/2] Don't clean away patches with conflicts

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

If we have conflicts, it means that the topmost patch is empty because
of those conflicts (since StGit explicitly makes a conflicting patch
empty), so don't let "stg clean" touch it.

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

---

I considered fixing this by way of a check in the shared
new-infrastructure code, but came to the conclusion that the check
really does belong in "stg clean".

 stgit/commands/clean.py |    7 +++++++
 stgit/lib/git.py        |    8 ++++++++
 t/t2500-clean.sh        |    2 +-
 3 files changed, 16 insertions(+), 1 deletions(-)


diff --git a/stgit/commands/clean.py b/stgit/commands/clean.py
index a0a0dca..889c1dc 100644
--- a/stgit/commands/clean.py
+++ b/stgit/commands/clean.py
@@ -40,6 +40,13 @@ def _clean(stack, clean_applied, clean_unapplied):
     trans = transaction.StackTransaction(stack, 'stg clean')
     def del_patch(pn):
         if pn in stack.patchorder.applied:
+            if pn == stack.patchorder.applied[-1]:
+                # We're about to clean away the topmost patch. Don't
+                # do that if we have conflicts, since that means the
+                # patch is only empty because the conflicts have made
+                # us dump its contents into the index and worktree.
+                if stack.repository.default_index.conflicts():
+                    return False
             return clean_applied and trans.patches[pn].data.is_nochange()
         elif pn in stack.patchorder.unapplied:
             return clean_unapplied and trans.patches[pn].data.is_nochange()
diff --git a/stgit/lib/git.py b/stgit/lib/git.py
index 2af1844..6cd7450 100644
--- a/stgit/lib/git.py
+++ b/stgit/lib/git.py
@@ -353,6 +353,14 @@ class Index(RunWithEnv):
     def delete(self):
         if os.path.isfile(self.__filename):
             os.remove(self.__filename)
+    def conflicts(self):
+        """The set of conflicting paths."""
+        paths = set()
+        for line in self.run(['git', 'ls-files', '-z', '--unmerged']
+                             ).raw_output().split('\0')[:-1]:
+            stat, path = line.split('\t', 1)
+            paths.add(path)
+        return paths
 
 class Worktree(object):
     def __init__(self, directory):
diff --git a/t/t2500-clean.sh b/t/t2500-clean.sh
index b38d868..ad8f892 100755
--- a/t/t2500-clean.sh
+++ b/t/t2500-clean.sh
@@ -35,7 +35,7 @@ test_expect_success 'Create a conflict' '
     ! stg push
 '
 
-test_expect_failure 'Make sure conflicting patches are preserved' '
+test_expect_success 'Make sure conflicting patches are preserved' '
     stg clean &&
     [ "$(echo $(stg applied))" = "p0 p2 p1" ] &&
     [ "$(echo $(stg unapplied))" = "" ]