git svn: fix shallow clone when upstream revision is too new

Thanks to Ka-Hing Cheung for the initial bug report and patch:
> git-svn uses $ra->get_latest_revnum to find out the latest
> revision, but that can be problematic, because get_latest_revnum
> returns the latest revnum in the entire repository, not
> restricted by whatever URL you used to construct $ra. So if you
> do git svn clone -r HEAD svn://blah/blah/trunk, it won't work if
> the latest checkin is in one of the branches (it will try to
> fetch a rev that doesn't exist in trunk, making the clone
> useless).

Relying on SVN::Core::INVALID_REVNUM (-1) as the "start"
argument to SVN::Ra::get_log() proved unreliable with http(s)
URLs so the result of SVN::Ra::get_latest_revnum() is used as
the "start" argument instead.

Signed-off-by: Eric Wong <normalperson@yhbt.net>

git-svn.perl

@@ -1647,6 +1647,7 @@ sub fetch_all {
 	my $ra = Git::SVN::Ra->new($url);
 	my $uuid = $ra->get_uuid;
 	my $head = $ra->get_latest_revnum;
+	$ra->get_log("", $head, 0, 1, 0, 1, sub { $head = $_[1] });
 	my $base = defined $fetch ? $head : 0;
 
 	# read the max revs for wildcard expansion (branches/*, tags/*)

t/t9142-git-svn-shallow-clone.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Eric Wong
+#
+
+test_description='git svn shallow clone'
+. ./lib-git-svn.sh
+
+test_expect_success 'setup test repository' '
+	svn_cmd mkdir -m "create standard layout" \
+	  "$svnrepo"/trunk "$svnrepo"/branches "$svnrepo"/tags &&
+	svn_cmd cp -m "branch off trunk" \
+	  "$svnrepo"/trunk "$svnrepo"/branches/a &&
+	svn_cmd co "$svnrepo"/branches/a &&
+	(
+		cd a &&
+		> foo &&
+		svn_cmd add foo &&
+		svn_cmd commit -m "add foo"
+	)
+'
+
+start_httpd
+
+test_expect_success 'clone trunk with "-r HEAD"' '
+	git svn clone -r HEAD "$svnrepo/trunk" g &&
+	( cd g && git rev-parse --symbolic --verify HEAD )
+'
+
+test_done