test-subrepo-git: ignore pax_global_header when listing archive

5115d03440f4 is adding a new tar call but forgot to filter out the
pax_global_header file that some tar versions write. This is similar to what
happened in 5dda6c708138.

tests/test-subrepo-git.t

@@ -326,7 +326,7 b' archive subrepos'
   ../archive_x/s/g
 
   $ hg -R ../tc archive -S ../archive.tgz --prefix '.' 2>/dev/null
-  $ tar -tzf ../archive.tgz | sort
+  $ tar -tzf ../archive.tgz | sort | grep -v pax_global_header
   .hg_archival.txt
   .hgsub
   .hgsubstate