show-ref: make --head always show the HEAD ref

The docs seem to say that doing

	git show-ref --head --tags

would show both the HEAD ref and all the tag refs. However, doing
both --head and either of --tags or --heads would filter out the HEAD
ref.

Also update the documentation to describe the new behavior and add
tests for the show-ref command.

[jc: Doug did proofread the tests, but it was done by me and bugs in
it are mine].

Signed-off-by: Doug Bell <madcityzen@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t1403-show-ref.sh b/t/t1403-show-ref.sh
new file mode 100755
index 0000000..3e500ed
--- /dev/null
+++ b/t/t1403-show-ref.sh
@@ -0,0 +1,167 @@
+#!/bin/sh
+
+test_description='show-ref'
+. ./test-lib.sh
+
+test_expect_success setup '
+	test_commit A &&
+	git tag -f -a -m "annotated A" A &&
+	git checkout -b side &&
+	test_commit B &&
+	git tag -f -a -m "annotated B" B &&
+	git checkout master &&
+	test_commit C &&
+	git branch B A^0
+'
+
+test_expect_success 'show-ref' '
+	echo $(git rev-parse refs/tags/A) refs/tags/A >expect &&
+
+	git show-ref A >actual &&
+	test_cmp expect actual &&
+
+	git show-ref tags/A >actual &&
+	test_cmp expect actual &&
+
+	git show-ref refs/tags/A >actual &&
+	test_cmp expect actual &&
+
+	>expect &&
+
+	test_must_fail git show-ref D >actual
+	test_cmp expect actual
+'
+
+test_expect_success 'show-ref -q' '
+	>expect &&
+
+	git show-ref -q A >actual &&
+	test_cmp expect actual &&
+
+	git show-ref -q tags/A >actual &&
+	test_cmp expect actual &&
+
+	git show-ref -q refs/tags/A >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git show-ref -q D >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'show-ref --verify' '
+	echo $(git rev-parse refs/tags/A) refs/tags/A >expect &&
+
+	git show-ref --verify refs/tags/A >actual &&
+	test_cmp expect actual &&
+
+	>expect &&
+
+	test_must_fail git show-ref --verify A >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git show-ref --verify tags/A >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git show-ref --verify D >actual
+	test_cmp expect actual
+'
+
+test_expect_success 'show-ref --verify -q' '
+	>expect &&
+
+	git show-ref --verify -q refs/tags/A >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git show-ref --verify -q A >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git show-ref --verify -q tags/A >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git show-ref --verify -q D >actual
+	test_cmp expect actual
+'
+
+test_expect_success 'show-ref -d' '
+	{
+		echo $(git rev-parse refs/tags/A) refs/tags/A &&
+		echo $(git rev-parse refs/tags/A^0) "refs/tags/A^{}"
+		echo $(git rev-parse refs/tags/C) refs/tags/C
+	} >expect &&
+	git show-ref -d A C >actual &&
+	test_cmp expect actual &&
+
+	git show-ref -d tags/A tags/C >actual &&
+	test_cmp expect actual &&
+
+	git show-ref -d refs/tags/A refs/tags/C >actual &&
+	test_cmp expect actual &&
+
+	echo $(git rev-parse refs/heads/master) refs/heads/master >expect &&
+	git show-ref -d master >actual &&
+	test_cmp expect actual &&
+
+	git show-ref -d heads/master >actual &&
+	test_cmp expect actual &&
+
+	git show-ref -d refs/heads/master >actual &&
+	test_cmp expect actual
+
+	git show-ref -d --verify refs/heads/master >actual &&
+	test_cmp expect actual
+
+	>expect &&
+
+	test_must_fail git show-ref -d --verify master >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git show-ref -d --verify heads/master >actual &&
+	test_cmp expect actual
+
+'
+
+test_expect_success 'show-ref --heads, --tags, --head, pattern' '
+	for branch in B master side
+	do
+		echo $(git rev-parse refs/heads/$branch) refs/heads/$branch
+	done >expect.heads &&
+	git show-ref --heads >actual &&
+	test_cmp expect.heads actual &&
+
+	for tag in A B C
+	do
+		echo $(git rev-parse refs/tags/$tag) refs/tags/$tag
+	done >expect.tags &&
+	git show-ref --tags >actual &&
+	test_cmp expect.tags actual &&
+
+	cat expect.heads expect.tags >expect &&
+	git show-ref --heads --tags >actual &&
+	test_cmp expect actual &&
+
+	{
+		echo $(git rev-parse HEAD) HEAD &&
+		cat expect.heads expect.tags
+	} >expect &&
+	git show-ref --heads --tags --head >actual &&
+	test_cmp expect actual &&
+
+	{
+		echo $(git rev-parse HEAD) HEAD &&
+		echo $(git rev-parse refs/heads/B) refs/heads/B
+		echo $(git rev-parse refs/tags/B) refs/tags/B
+	} >expect &&
+	git show-ref --head B >actual &&
+	test_cmp expect actual &&
+
+	{
+		echo $(git rev-parse HEAD) HEAD &&
+		echo $(git rev-parse refs/heads/B) refs/heads/B
+		echo $(git rev-parse refs/tags/B) refs/tags/B
+		echo $(git rev-parse refs/tags/B^0) "refs/tags/B^{}"
+	} >expect &&
+	git show-ref --head -d B >actual &&
+	test_cmp expect actual
+'
+
+test_done