gzip: indent the custom Gzip code

We need a new conditional in the next changesets (Adding 3.8 support). We do the
large code move beforehand for clarity.

mercurial/archival.py

@@ -135,6 +135,8 b' class tarit(object):'
     '''write archive to tar file or stream.  can write uncompressed,
     or compress with gzip or bzip2.'''
 
+    if True:
+
     class GzipFileWithTime(gzip.GzipFile):
         def __init__(self, *args, **kw):
             timestamp = None