import-tars: be nice to wrong directory modes

Some tars seem to have modes 0755 for directories, not 01000755. Do
not generate an empty object for them, but ignore them.

Noticed by riddochc on IRC.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

contrib/fast-import/import-tars.perl

@@ -52,6 +52,7 @@ foreach my $tar_file (@ARGV)
 			Z8 Z1 Z100 Z6
 			Z2 Z32 Z32 Z8 Z8 Z*', $_;
 		last unless $name;
+		next if $name =~ '/$';
 		$mode = oct $mode;
 		$size = oct $size;
 		$mtime = oct $mtime;