Stop assuming .git is a directory in gitmerge.el

* admin/gitmerge.el (gitmerge-maybe-resume): Use 'git rev-parse
--git-dir' to find the git directory rather than assuming it is
.git/ (that assumption fails for separated worktrees).

1 files changed, 6 insertions, 2 deletions

diff --git a/admin/gitmerge.el b/admin/gitmerge.el
index e676e8fa025..a123e0352d7 100644
--- a/admin/gitmerge.el
+++ b/admin/gitmerge.el
@@ -483,8 +483,12 @@ Throw an user-error if we cannot resolve automatically."
 (defun gitmerge-maybe-resume ()
   "Check if we have to resume a merge.
 If so, add no longer conflicted files and commit."
-  (let ((mergehead (file-exists-p
-                    (expand-file-name ".git/MERGE_HEAD" default-directory)))
+  (let ((mergehead
+         (file-exists-p
+          (expand-file-name
+           "MERGE_HEAD"
+           (car (process-lines
+                 "git" "rev-parse" "--no-flags" "--git-dir")))))
         (statusexist (file-exists-p gitmerge-status-file)))
     (when (and mergehead (not statusexist))
       (user-error "Unfinished merge, but no record of a previous gitmerge run"))