[PATCH 06 of 11] changegroup: use compression engines API

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1477158873 25200
#      Sat Oct 22 10:54:33 2016 -0700
# Node ID 86eced535f53fc2992c44eef2ecd6231d3c7f33c
# Parent  859682e2187c46bb7ab68aedd7dcbab5266d878e
changegroup: use compression engines API

The new API doesn't have the equivalence for None and 'UN' so we
introduce code to use 'UN' explicitly.

diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -132,24 +132,26 @@ class cg1unpacker(object):
     bundlerepo and some debug commands - their use is discouraged.
     """
     deltaheader = _CHANGEGROUPV1_DELTA_HEADER
     deltaheadersize = struct.calcsize(deltaheader)
     version = '01'
     _grouplistcount = 1 # One list of files after the manifests
 
     def __init__(self, fh, alg, extras=None):
-        if alg == 'UN':
-            alg = None # get more modern without breaking too much
-        if not alg in util.decompressors:
+        if alg is None:
+            alg = 'UN'
+        if alg not in util.compressionengines.supportedbundletypes:
             raise error.Abort(_('unknown stream compression type: %s')
                              % alg)
         if alg == 'BZ':
             alg = '_truncatedBZ'
-        self._stream = util.decompressors[alg](fh)
+
+        compengine = util.compressionengines.forbundletype(alg)
+        self._stream = compengine.decompressorreader(fh)
         self._type = alg
         self.extras = extras or {}
         self.callback = None
 
     # These methods (compressed, read, seek, tell) all appear to only
     # be used by bundlerepo, but it's a little hard to tell.
     def compressed(self):
         return self._type is not None