Fix refdb iteration early termination bug

There was a problem found in the Rugged test suite where the
refdb_fs_backend__next function could exit too early in some
very specific hashing patterns for packed refs.  This ports
the Rugged test to libgit2 and then fixes the bug.

src/refdb_fs.c

@@ -671,17 +671,20 @@ static int refdb_fs_backend__next(const char **out, git_reference_iterator *_ite
 {
 	refdb_fs_iter *iter = (refdb_fs_iter *)_iter;
 
-	/* First round of checks to make sure where we are */
-	if (!iter->loose && iter->k == kh_end(iter->h)) {
-		if (iter_loose_setup(iter) < 0)
-			return -1;
-		iter->loose = 1;
+	if (iter->loose)
+		return iter_loose(out, iter);
+
+	if (iter->k != kh_end(iter->h)) {
+		int error = iter_packed(out, iter);
+		if (error != GIT_ITEROVER)
+			return error;
 	}
 
-	if (!iter->loose)
-		return iter_packed(out, iter);
-	else
-		return iter_loose(out, iter);
+	if (iter_loose_setup(iter) < 0)
+		return -1;
+	iter->loose = 1;
+
+	return iter_loose(out, iter);
 }
 
 static int loose_write(refdb_fs_backend *backend, const git_reference *ref)

tests-clar/refs/branches/foreach.c

@@ -24,6 +24,8 @@ void test_refs_branches_foreach__cleanup(void)
 	repo = NULL;
 
 	cl_fixture_cleanup("testrepo.git");
+
+	cl_git_sandbox_cleanup();
 }
 
 static int count_branch_list_cb(const char *branch_name, git_branch_t branch_type, void *payload)
@@ -72,14 +74,11 @@ static void assert_branch_has_been_found(struct expectations *findings, const ch
 {
 	int pos = 0;
 
-	while (findings[pos].branch_name)
-	{
+	for (pos = 0; findings[pos].branch_name; ++pos) {
 		if (strcmp(expected_branch_name, findings[pos].branch_name) == 0) {
 			cl_assert_equal_i(1, findings[pos].encounters);
 			return;
 		}
-
-		pos++;
 	}
 
 	cl_fail("expected branch not found in list.");
@@ -94,12 +93,9 @@ static int contains_branch_list_cb(const char *branch_name, git_branch_t branch_
 
 	exp = (struct expectations *)payload;
 
-	while (exp[pos].branch_name)
-	{
+	for (pos = 0; exp[pos].branch_name; ++pos) {
 		if (strcmp(branch_name, exp[pos].branch_name) == 0)
 			exp[pos].encounters++;
-		
-		pos++;
 	}
 
 	return 0;
@@ -153,3 +149,25 @@ void test_refs_branches_foreach__can_cancel(void)
 
 	cl_assert_equal_i(5, count);
 }
+
+void test_refs_branches_foreach__mix_of_packed_and_loose(void)
+{
+	struct expectations exp[] = {
+		{ "master", 0 },
+		{ "origin/HEAD", 0 },
+		{ "origin/master", 0 },
+		{ "origin/packed", 0 },
+		{ NULL, 0 }
+	};
+	git_repository *r2;
+
+	r2 = cl_git_sandbox_init("testrepo2");
+
+	cl_git_pass(git_branch_foreach(r2, GIT_BRANCH_LOCAL | GIT_BRANCH_REMOTE,
+		contains_branch_list_cb, &exp));
+
+	assert_branch_has_been_found(exp, "master");
+	assert_branch_has_been_found(exp, "origin/HEAD");
+	assert_branch_has_been_found(exp, "origin/master");
+	assert_branch_has_been_found(exp, "origin/packed");
+}

tests-clar/resources/testrepo2/.gitted/HEAD

+ref: refs/heads/master

tests-clar/resources/testrepo2/.gitted/config

+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = false
+	logallrefupdates = true
+	ignorecase = true
+	precomposeunicode = false
+[remote "origin"]
+	url = https://github.com/libgit2/false.git
+	fetch = +refs/heads/*:refs/remotes/origin/*
+[branch "master"]
+	remote = origin
+	merge = refs/heads/master
+	rebase = true

tests-clar/resources/testrepo2/.gitted/description

+Unnamed repository; edit this file 'description' to name the repository.

tests-clar/resources/testrepo2/.gitted/info/exclude

+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

tests-clar/resources/testrepo2/.gitted/logs/HEAD

+0000000000000000000000000000000000000000 36060c58702ed4c2a40832c51758d5344201d89a Russell Belfer <rb@github.com> 1368278260 -0700	clone: from /Users/rb/src/libgit2/tests-clar/resources/../../../rugged/test/fixtures/testrepo.git

tests-clar/resources/testrepo2/.gitted/logs/refs/heads/master

+0000000000000000000000000000000000000000 36060c58702ed4c2a40832c51758d5344201d89a Russell Belfer <rb@github.com> 1368278260 -0700	clone: from /Users/rb/src/libgit2/tests-clar/resources/../../../rugged/test/fixtures/testrepo.git

tests-clar/resources/testrepo2/.gitted/logs/refs/remotes/origin/HEAD

+0000000000000000000000000000000000000000 36060c58702ed4c2a40832c51758d5344201d89a Russell Belfer <rb@github.com> 1368278260 -0700	clone: from /Users/rb/src/libgit2/tests-clar/resources/../../../rugged/test/fixtures/testrepo.git

tests-clar/resources/testrepo2/.gitted/packed-refs

+# pack-refs with: peeled fully-peeled 
+36060c58702ed4c2a40832c51758d5344201d89a refs/remotes/origin/master
+41bc8c69075bbdb46c5c6f0566cc8cc5b46e8bd9 refs/remotes/origin/packed
+5b5b025afb0b4c913b4c338a42934a3863bf3644 refs/tags/v0.9
+0c37a5391bbff43c37f0d0371823a5509eed5b1d refs/tags/v1.0
+^5b5b025afb0b4c913b4c338a42934a3863bf3644

tests-clar/resources/testrepo2/.gitted/refs/heads/master

+36060c58702ed4c2a40832c51758d5344201d89a

tests-clar/resources/testrepo2/.gitted/refs/remotes/origin/HEAD

+ref: refs/remotes/origin/master

tests-clar/resources/testrepo2/README

+hey

tests-clar/resources/testrepo2/new.txt

+new file

tests-clar/resources/testrepo2/subdir/README

+hey

tests-clar/resources/testrepo2/subdir/new.txt

+new file

tests-clar/resources/testrepo2/subdir/subdir2/README

+hey

tests-clar/resources/testrepo2/subdir/subdir2/new.txt

+new file