remotefilelog: remove some BC code related to streamclone

Since remotefilelog is now moved to core and we have
streamclone._walkstreamfiles() in core, we don't need to have the backward
compatibility code.

People with old mercurial version should use remotefilelog from hg-experimental
repo as IMO remotefilelog will go under a good refactoring and old clients will
break.

# no-check-commit foo_bar function name

Differential Revision: https://phab.mercurial-scm.org/D5189

hgext/remotefilelog/__init__.py

@@ -121,6 +121,7 b' from mercurial import ('
     revset,
     scmutil,
     smartset,
+    streamclone,
     templatekw,
     util,
 )
@@ -142,13 +143,6 b' from . import ('
 # ensures debug commands are registered
 hgdebugcommands.command
 
-try:
-    from mercurial import streamclone
-    streamclone._walkstreamfiles
-    hasstreamclone = True
-except Exception:
-    hasstreamclone = False
-
 cmdtable = {}
 command = registrar.command(cmdtable)
 
@@ -305,7 +299,6 b' def cloneshallow(orig, ui, repo, *args, '
                 else:
                     return orig()
             extensions.wrapfunction(remote, 'stream_out', stream_out_shallow)
-        if hasstreamclone:
             def stream_wrap(orig, op):
                 setup_streamout(op.repo, op.remote)
                 return orig(op)
@@ -328,13 +321,6 b' def cloneshallow(orig, ui, repo, *args, '
                 return supported, requirements
             extensions.wrapfunction(
                 streamclone, 'canperformstreamclone', canperformstreamclone)
-        else:
-            def stream_in_shallow(orig, repo, remote, requirements):
-                setup_streamout(repo, remote)
-                requirements.add(constants.SHALLOWREPO_REQUIREMENT)
-                return orig(repo, remote, requirements)
-            extensions.wrapfunction(
-                localrepo.localrepository, 'stream_in', stream_in_shallow)
 
     try:
         orig(ui, repo, *args, **opts)