wt-status.c: set commitable bit if there is a meaningful merge.

The 'commit --dry-run' and 'commit' return values differed if a
conflicted merge had been resolved and the resulting commit would
record the same tree as the parent.

Update show_merge_in_progress to set the commitable bit if conflicts
have been resolved and a merge is in progress.

Signed-off-by: Stephen P. Smith <ischis2@cox.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7501-commit.sh

@@ -587,4 +587,24 @@ test_expect_success '--only works on to-be-born branch' '
 	test_cmp expected actual
 '
 
+test_expect_success '--dry-run with conflicts fixed from a merge' '
+	# setup two branches with conflicting information
+	# in the same file, resolve the conflict,
+	# call commit with --dry-run
+	echo "Initial contents, unimportant" >test-file &&
+	git add test-file &&
+	git commit -m "Initial commit" &&
+	echo "commit-1-state" >test-file &&
+	git commit -m "commit 1" -i test-file &&
+	git tag commit-1 &&
+	git checkout -b branch-2 HEAD^1 &&
+	echo "commit-2-state" >test-file &&
+	git commit -m "commit 2" -i test-file &&
+	! $(git merge --no-commit commit-1) &&
+	echo "commit-2-state" >test-file &&
+	git add test-file &&
+	git commit --dry-run &&
+	git commit -m "conflicts fixed from merge."
+'
+
 test_done

wt-status.c

@@ -949,6 +949,7 @@ static void show_merge_in_progress(struct wt_status *s,
 			status_printf_ln(s, color,
 				_("  (fix conflicts and run \"git commit\")"));
 	} else {
+		s-> commitable = 1;
 		status_printf_ln(s, color,
 			_("All conflicts fixed but you are still merging."));
 		if (s->hints)