git-svn: add a message encouraging use of SVN::* libraries

I'm using svn 1.4.0-4 in Debian unstable and apparently there's
a regression on the SVN side that prevents a symlink from
becoming a regular file (which git supports, of course).

It's not a noticeable regression for most people, but this broke
the full-svn-tests target in t/Makefile for me.

The SVN::* Perl libraries seem to have matured and improved over
the past year, and git-svn has supported them for several months
now, so with that I encourage all users to start using the
SVN::* Perl libraries with git-svn.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-svn.perl

@@ -40,8 +40,22 @@
 memoize('get_commit_time');
 
 my ($SVN_PATH, $SVN, $SVN_LOG, $_use_lib);
+
+sub nag_lib {
+	print STDERR <<EOF;
+! Please consider installing the SVN Perl libraries (version 1.1.0 or
+! newer).  You will generally get better performance and fewer bugs,
+! especially if you:
+! 1) have a case-insensitive filesystem
+! 2) replace symlinks with files (and vice-versa) in commits
+
+EOF
+}
+
 $_use_lib = 1 unless $ENV{GIT_SVN_NO_LIB};
 libsvn_load();
+nag_lib() unless $_use_lib;
+
 my $_optimize_commits = 1 unless $ENV{GIT_SVN_NO_OPTIMIZE_COMMITS};
 my $sha1 = qr/[a-f\d]{40}/;
 my $sha1_short = qr/[a-f\d]{4,40}/;