git-svn: fix mismatched src/dst errors for branch/tag

This fixes the following issue:

$ git svn branch -t --username=svnuser \
  --commit-url=https://myproj.domain.com/svn mytag
Copying http://myproj.domain.com/svn/trunk at r26 to
https://myproj.domain.com/svn/tags/mytag...

Trying to use an unsupported feature: Source and dest appear not to be
in the same repository (src: 'http://myproj.domain.com/svn/trunk';
dst: 'https://myproj.domain.com/svn/tags/mytag')

[ew: shortened subject]

Signed-off-by: Igor Mironov <igor.a.mironov@gmail.com>
Acked-by: Eric Wong <normalperson@yhbt.net>

git-svn.perl

@@ -710,6 +710,10 @@ sub cmd_branch {
 	my ($lft, $rgt) = @{ $glob->{path} }{qw/left right/};
 	my $dst = join '/', $remote->{url}, $lft, $branch_name, ($rgt || ());
 
+	if ($dst =~ /^https:/ && $src =~ /^http:/) {
+		$src=~s/^http:/https:/;
+	}
+
 	my $ctx = SVN::Client->new(
 		auth    => Git::SVN::Ra::_auth_providers(),
 		log_msg => sub {