git-svn: fix fetch with deleted tag

Currently git-svn assumes that two tags created from the same
revision will have the same repo url, so it uses a ref to the
tag without checking that its url matches the current url.

This causes issues when fetching an svn repo where a tag was
created, deleted, and then recreated under the following
circumstances:

- Both tags were copied from the same revision.
- Both tags had the same name.
- Both tags had different repository paths.
- [Optional] Both tags have a file with the same name but
  different content.

When all four conditions are met, a checksum mismatch error
occurs because the content of two files with the same path
differs (see t/t9155--git-svn-fetch-deleted-tag.sh):

    Checksum mismatch: ChangeLog 065854....
    expected: ce771b....
         got: 9563fd....

When only the first three conditions are met, no error occurs
but the tag in git matches the first (deleted) tag instead of
the last (most recent) tag (see
t/t9156-git-svn-fetch-deleted-tag-2.sh).

The fix is to verify that the repo url for the ref matches the
current url.  If the urls do not match, then a "tail" is grown
on the tag name by appending a dash and rechecking the new ref's
repo url until either a matching repo url is found or a new tag
is created.

Signed-off-by: David D. Kilzer <ddkilzer@kilzer.net>
Acked-by: Eric Wong <normalperson@yhbt.net>

git-svn.perl

@@ -2963,14 +2963,25 @@ sub other_gs {
 		$ref_id .= "\@$r";
 		# just grow a tail if we're not unique enough :x
 		$ref_id .= '-' while find_ref($ref_id);
-		print STDERR "Initializing parent: $ref_id\n" unless $::_q > 1;
 		my ($u, $p, $repo_id) = ($new_url, '', $ref_id);
 		if ($u =~ s#^\Q$url\E(/|$)##) {
 			$p = $u;
 			$u = $url;
 			$repo_id = $self->{repo_id};
 		}
-		$gs = Git::SVN->init($u, $p, $repo_id, $ref_id, 1);
+		while (1) {
+			# It is possible to tag two different subdirectories at
+			# the same revision.  If the url for an existing ref
+			# does not match, we must either find a ref with a
+			# matching url or create a new ref by growing a tail.
+			$gs = Git::SVN->init($u, $p, $repo_id, $ref_id, 1);
+			my (undef, $max_commit) = $gs->rev_map_max(1);
+			last if (!$max_commit);
+			my ($url) = ::cmt_metadata($max_commit);
+			last if ($url eq $gs->full_url);
+			$ref_id .= '-';
+		}
+		print STDERR "Initializing parent: $ref_id\n" unless $::_q > 1;
 	}
 	$gs
 }

t/t9155-git-svn-fetch-deleted-tag.sh

@@ -0,0 +1,42 @@
+#!/bin/sh
+
+test_description='git svn fetch deleted tag'
+
+. ./lib-git-svn.sh
+
+test_expect_success 'setup svn repo' '
+	mkdir -p import/trunk/subdir &&
+	mkdir -p import/branches &&
+	mkdir -p import/tags &&
+	echo "base" >import/trunk/subdir/file &&
+	svn_cmd import -m "import for git svn" import "$svnrepo" &&
+	rm -rf import &&
+
+	svn_cmd mkdir --parents -m "create mybranch directory" "$svnrepo/branches/mybranch" &&
+	svn_cmd cp -m "create branch mybranch" "$svnrepo/trunk" "$svnrepo/branches/mybranch/trunk" &&
+
+	svn_cmd co "$svnrepo/trunk" svn_project &&
+	(cd svn_project &&
+		echo "trunk change" >>subdir/file &&
+		svn_cmd ci -m "trunk change" subdir/file &&
+
+		svn_cmd switch "$svnrepo/branches/mybranch/trunk" &&
+		echo "branch change" >>subdir/file &&
+		svn_cmd ci -m "branch change" subdir/file
+	) &&
+
+	svn_cmd cp -m "create mytag attempt 1" -r5 "$svnrepo/trunk/subdir" "$svnrepo/tags/mytag" &&
+	svn_cmd rm -m "delete mytag attempt 1" "$svnrepo/tags/mytag" &&
+	svn_cmd cp -m "create mytag attempt 2" -r5 "$svnrepo/branches/mybranch/trunk/subdir" "$svnrepo/tags/mytag"
+'
+
+test_expect_success 'fetch deleted tags from same revision with checksum error' '
+	git svn init --stdlayout "$svnrepo" git_project &&
+	cd git_project &&
+	git svn fetch &&
+
+	git diff --exit-code mybranch:trunk/subdir/file tags/mytag:file &&
+	git diff --exit-code master:subdir/file tags/mytag^:file
+'
+
+test_done

t/t9156-git-svn-fetch-deleted-tag-2.sh

@@ -0,0 +1,44 @@
+#!/bin/sh
+
+test_description='git svn fetch deleted tag 2'
+
+. ./lib-git-svn.sh
+
+test_expect_success 'setup svn repo' '
+	mkdir -p import/branches &&
+	mkdir -p import/tags &&
+	mkdir -p import/trunk/subdir1 &&
+	mkdir -p import/trunk/subdir2 &&
+	mkdir -p import/trunk/subdir3 &&
+	echo "file1" >import/trunk/subdir1/file &&
+	echo "file2" >import/trunk/subdir2/file &&
+	echo "file3" >import/trunk/subdir3/file &&
+	svn_cmd import -m "import for git svn" import "$svnrepo" &&
+	rm -rf import &&
+
+	svn_cmd co "$svnrepo/trunk" svn_project &&
+	(cd svn_project &&
+		echo "change1" >>subdir1/file &&
+		echo "change2" >>subdir2/file &&
+		echo "change3" >>subdir3/file &&
+		svn_cmd ci -m "change" .
+	) &&
+
+	svn_cmd cp -m "create mytag 1" -r2 "$svnrepo/trunk/subdir1" "$svnrepo/tags/mytag" &&
+	svn_cmd rm -m "delete mytag 1" "$svnrepo/tags/mytag" &&
+	svn_cmd cp -m "create mytag 2" -r2 "$svnrepo/trunk/subdir2" "$svnrepo/tags/mytag" &&
+	svn_cmd rm -m "delete mytag 2" "$svnrepo/tags/mytag" &&
+	svn_cmd cp -m "create mytag 3" -r2 "$svnrepo/trunk/subdir3" "$svnrepo/tags/mytag"
+'
+
+test_expect_success 'fetch deleted tags from same revision with no checksum error' '
+	git svn init --stdlayout "$svnrepo" git_project &&
+	cd git_project &&
+	git svn fetch &&
+
+	git diff --exit-code master:subdir3/file tags/mytag:file &&
+	git diff --exit-code master:subdir2/file tags/mytag^:file &&
+	git diff --exit-code master:subdir1/file tags/mytag^^:file
+'
+
+test_done