git-cvsimport: fix handling of user name when it is not set in CVSROOT

The cvs programs do not default to "anonymous" as the user name, but use the
currently logged in user.  This patch more closely matches the cvs behavior.

Signed-off-by: Gordon Hopper <g.hopper@computer.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-cvsimport.perl

@@ -223,7 +223,8 @@ sub conn {
 			}
 		}
 
-		$user="anonymous" unless defined $user;
+		# if username is not explicit in CVSROOT, then use current user, as cvs would
+		$user=(getlogin() || $ENV{'LOGNAME'} || $ENV{'USER'} || "anonymous") unless $user;
 		my $rr2 = "-";
 		unless ($port) {
 			$rr2 = ":pserver:$user\@$serv:$repo";