[PATCH] Fix for a merge where a branch has an F->D transition

[Alex Riesen <raa.lkml@gmail.com>]

Some path names which transitioned from file to a directory were not
updated in the final part of the merge (loop around unmerged entries in
merge_trees), because the branch in process_renames which filtered out
updates for the files with the same content ("merged same as existing")
has left the rename entry in processed state. In this case, the
processing cannot be finished at the process_renames phase (because
the old file still blocks creation of directory where new files should
appear), and must be postponed until the update_entry phase.

Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
---

Alex Riesen, Mon, May 11, 2009 11:42:17 +0200:
> The problem is that if a file was replaced with a directory containing
> another file with the same content and mode, an attempt to merge it
> with a branch descended from a commit before this F->D transition will
> cause merge-recursive to break. It breaks even if there were no
> conflicting changes on that other branch.
> 
> 2009/5/11 Johannes Schindelin <Johannes.Schindelin@gmx.de>:
> >
> > Maybe you can turn this into a patch adding a test (with
> > test_expect_failure to mark it as a bug)?  This would make debugging a lot
> > easier, as a non-installed Git could be tested.
> 
> Here.
> 
>  t/t6020-merge-df.sh |   23 +++++++++++++++++++++++
>  1 files changed, 23 insertions(+), 0 deletions(-)
> 

Frankly, I'm not really sure. The solution came largely ... empirical
way. IOW, I tried more or less random things which looked like they
should fix the problem. So a review is very much appreciated. Please.

 merge-recursive.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index a3721ef..3c5420b 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -980,14 +980,15 @@ static int process_renames(struct merge_options *o,
 
 				if (mfi.clean &&
 				    sha_eq(mfi.sha, ren1->pair->two->sha1) &&
-				    mfi.mode == ren1->pair->two->mode)
+				    mfi.mode == ren1->pair->two->mode) {
 					/*
 					 * This messaged is part of
 					 * t6022 test. If you change
 					 * it update the test too.
 					 */
 					output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
-				else {
+					ren1->dst_entry->processed = 0;
+				} else {
 					if (mfi.merge || !mfi.clean)
 						output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
 					if (mfi.merge)
-- 
1.6.3.28.ga852b