Merge branch 'jk/alt-odb-cleanup'

Fix a corner-case regression in a topic that graduated during the
v2.11 cycle.

* jk/alt-odb-cleanup:
  alternates: re-allow relative paths from environment

sha1_file.c

@@ -296,7 +296,7 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base,
 	}
 	strbuf_addstr(&pathbuf, entry);
 
-	if (strbuf_normalize_path(&pathbuf) < 0) {
+	if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 		error("unable to normalize alternate object path: %s",
 		      pathbuf.buf);
 		strbuf_release(&pathbuf);

t/t5615-alternate-env.sh

@@ -0,0 +1,71 @@
+#!/bin/sh
+
+test_description='handling of alternates in environment variables'
+. ./test-lib.sh
+
+check_obj () {
+	alt=$1; shift
+	while read obj expect
+	do
+		echo "$obj" >&3 &&
+		echo "$obj $expect" >&4
+	done 3>input 4>expect &&
+	GIT_ALTERNATE_OBJECT_DIRECTORIES=$alt \
+		git "$@" cat-file --batch-check='%(objectname) %(objecttype)' \
+		<input >actual &&
+	test_cmp expect actual
+}
+
+test_expect_success 'create alternate repositories' '
+	git init --bare one.git &&
+	one=$(echo one | git -C one.git hash-object -w --stdin) &&
+	git init --bare two.git &&
+	two=$(echo two | git -C two.git hash-object -w --stdin)
+'
+
+test_expect_success 'objects inaccessible without alternates' '
+	check_obj "" <<-EOF
+	$one missing
+	$two missing
+	EOF
+'
+
+test_expect_success 'access alternate via absolute path' '
+	check_obj "$(pwd)/one.git/objects" <<-EOF
+	$one blob
+	$two missing
+	EOF
+'
+
+test_expect_success 'access multiple alternates' '
+	check_obj "$(pwd)/one.git/objects:$(pwd)/two.git/objects" <<-EOF
+	$one blob
+	$two blob
+	EOF
+'
+
+# bare paths are relative from $GIT_DIR
+test_expect_success 'access alternate via relative path (bare)' '
+	git init --bare bare.git &&
+	check_obj "../one.git/objects" -C bare.git <<-EOF
+	$one blob
+	EOF
+'
+
+# non-bare paths are relative to top of worktree
+test_expect_success 'access alternate via relative path (worktree)' '
+	git init worktree &&
+	check_obj "../one.git/objects" -C worktree <<-EOF
+	$one blob
+	EOF
+'
+
+# path is computed after moving to top-level of worktree
+test_expect_success 'access alternate via relative path (subdir)' '
+	mkdir subdir &&
+	check_obj "one.git/objects" -C subdir <<-EOF
+	$one blob
+	EOF
+'
+
+test_done