push: use same rules as git-rev-parse to resolve refspecs

This commit changes the rules for resolving refspecs to match the
rules for resolving refs in rev-parse. git-rev-parse uses clear rules
to resolve a short ref to its full name, which are well documented.
The rules for resolving refspecs documented in git-send-pack were
less strict and harder to understand. This commit replaces them by
the rules of git-rev-parse.

The unified rules are easier to understand and better resolve ambiguous
cases. You can now push from a repository containing several branches
ending on the same short name.

Note, this may break existing setups. For example, "master" will no longer
resolve to "origin/master" even when there is no other "master" elsewhere.

Signed-off-by: Steffen Prohaska <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Documentation/git-send-pack.txt

@@ -85,7 +85,9 @@ Each pattern pair consists of the source side (before the colon)
 and the destination side (after the colon).  The ref to be
 pushed is determined by finding a match that matches the source
 side, and where it is pushed is determined by using the
-destination side.
+destination side. The rules used to match a ref are the same
+rules used by gitlink:git-rev-parse[1] to resolve a symbolic ref
+name.
 
  - It is an error if <src> does not match exactly one of the
    local refs.

remote.c

@@ -519,10 +519,7 @@ static int count_refspec_match(const char *pattern,
 		char *name = refs->name;
 		int namelen = strlen(name);
 
-		if (namelen < patlen ||
-		    memcmp(name + namelen - patlen, pattern, patlen))
-			continue;
-		if (namelen != patlen && name[namelen - patlen - 1] != '/')
+		if (!refname_match(pattern, name, ref_rev_parse_rules))
 			continue;
 
 		/* A match is "weak" if it is with refs outside

t/t5516-fetch-push.sh

@@ -145,11 +145,21 @@ test_expect_success 'push with no ambiguity (1)' '
 test_expect_success 'push with no ambiguity (2)' '
 
 	mk_test remotes/origin/master &&
-	git push testrepo master:master &&
+	git push testrepo master:origin/master &&
 	check_push_result $the_commit remotes/origin/master
 
 '
 
+test_expect_success 'push with colon-less refspec, no ambiguity' '
+
+	mk_test heads/master heads/t/master &&
+	git branch -f t/master master &&
+	git push testrepo master &&
+	check_push_result $the_commit heads/master &&
+	check_push_result $the_first_commit heads/t/master
+
+'
+
 test_expect_success 'push with weak ambiguity (1)' '
 
 	mk_test heads/master remotes/origin/master &&