git-svn: Fix fetch --no-ignore-externals with GIT_SVN_NO_LIB=1

When using Subversion 1.3.1 without Perl bindings (GIT_SVN_NO_LIB=1),
"git-svn fetch --no-ignore-externals" fails with errors like:

  Tree (.../.git/svn/git-svn/tree) is not clean:
  X      directory_with_external

In this case the 'X' lines in the "svn status" output are not a sign
of unclean tree, and therefore should be ignored.

Signed-off-by: Sergey Vlasov <vsu@altlinux.ru>
Acked-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-svn.perl

@@ -1247,6 +1247,7 @@ sub assert_svn_wc_clean {
 	}
 	my @status = grep(!/^Performing status on external/,(`svn status`));
 	@status = grep(!/^\s*$/,@status);
+	@status = grep(!/^X/,@status) if $_no_ignore_ext;
 	if (scalar @status) {
 		print STDERR "Tree ($SVN_WC) is not clean:\n";
 		print STDERR $_ foreach @status;