Ignore pax_global_header that some tar versions write as a file.

tests/test-subrepo-git.t

@@ -301,6 +301,6 b' nested commit'
 nested archive
 
   $ hg archive --subrepos ../narchive
-  $ ls ../narchive/inner/s
+  $ ls ../narchive/inner/s | grep -v pax_global_header
   f
   g