work around a bug in git

http://marc.info/?l=git&m=140262402204212&w=2

This git bug manifested on FAT and Windows as the test suite failing in 3
places. All involved merge conflict resolution. It turned out that the
associated file mappings were getting messed up, and that happened because
this git bug lost track of what files were supposed to be symlinks.

This commit was sponsored by Eric Kidd.

doc/bugs/direct_mode_merge_interrupt.mdwn

@@ -32,8 +32,16 @@ merge. (I assume this is how `git merge` normally works.) --[[Joey]]
 > Seems that a direct mode
 > merge also needs to use a different index file to stage its changes?
 > (Ugh)
-> > [[done]] --[[Joey]]
-> 
+> > done --[[Joey]]
+
+> > > I had to revert the fix on FAT/Windows due to 
+> > > a git bug: <http://marc.info/?l=git&m=140262402204212&w=2>
+> > > Once that bug's fixed, I can revisit this. --[[Joey]]
+
+[[!meta title="direct mode merge interrupt (fixed for all except FAT, Windows)"]]
+
+## other options
+
 > Or could perhaps use `git-merge-tree`
 > and avoid staging the merge in the index until the work-tree is updated.
 >