merge: indicate remote tracking branches in merge message

Previously when merging directly from a local tracking
branch like:

  git merge origin/master

The merge message said:

   Merge commit 'origin/master'

     * commit 'origin/master':
       ...

Instead, let's be more explicit about what we are merging:

   Merge remote branch 'origin/master'

     * origin/master:
       ...

We accomplish this by recognizing remote tracking branches
in git-merge when we build the simulated FETCH_HEAD output
that we feed to fmt-merge-msg.

In addition to a new test in t7608, we have to tweak the
expected output of t3409, which does such a merge.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/builtin-merge.c b/builtin-merge.c
index f7db14846e..f4de73fa9d 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -375,6 +375,11 @@ static void merge_name(const char *remote, struct strbuf *msg)
 				    sha1_to_hex(branch_head), remote);
 			goto cleanup;
 		}
+		if (!prefixcmp(found_ref, "refs/remotes/")) {
+			strbuf_addf(msg, "%s\t\tremote branch '%s' of .\n",
+				    sha1_to_hex(branch_head), remote);
+			goto cleanup;
+		}
 	}
 
 	/* See if remote matches <name>^^^.. or <name>~<number> */