bundle2: introduce a bundle2caps function

The process of decoding remote bundle2caps blob into a dictionary is cumbersome.
We move it into a small helper function. This will clarify code that reads
bundle2 capabilities of peers and helps using it in new places.

mercurial/bundle2.py

@@ -769,6 +769,13 b' class unbundlepart(unpackermixin):'
             self.consumed = True
         return data
 
+def bundle2caps(remote):
+    """return the bundlecapabilities of a peer as dict"""
+    raw = remote.capable('bundle2-exp')
+    if not raw and raw != '':
+        return {}
+    capsblob = urllib.unquote(remote.capable('bundle2-exp'))
+    return decodecaps(capsblob)
 
 @parthandler('b2x:changegroup')
 def handlechangegroup(op, inpart):

mercurial/exchange.py

@@ -208,9 +208,7 b' def _pushbundle2(pushop):'
 
     The only currently supported type of data is changegroup but this will
     evolve in the future."""
-    capsblob = urllib.unquote(pushop.remote.capable('bundle2-exp'))
-    caps = bundle2.decodecaps(capsblob)
-    bundler = bundle2.bundle20(pushop.ui, caps)
+    bundler = bundle2.bundle20(pushop.ui, bundle2.bundle2caps(pushop.remote))
     # create reply capability
     capsblob = bundle2.encodecaps(pushop.repo.bundle2caps)
     bundler.newpart('b2x:replycaps', data=capsblob)