--- a/hgext3rd/evolve/obsexchange.py	Mon Feb 26 13:59:30 2018 +0100
+++ b/hgext3rd/evolve/obsexchange.py	Fri Mar 02 16:30:48 2018 -0500
@@ -25,9 +25,14 @@
     pushkey,
     util,
     wireproto,
-    wireprotoserver,
 )
 
+try:
+    from mercurial import wireprotoserver
+    wireprotoserver.parsehttprequest
+except ImportError:
+    wireprotoserver = None
+
 from mercurial.hgweb import common as hgwebcommon
 
 from . import (
@@ -231,25 +236,26 @@
         raise err
     return {}
 
-# reinstall dispatch catching ResponseError as in hg 4.5 <
-@eh.wrapfunction(wireprotoserver, 'parsehttprequest')
-def parsehttprequest(orig, repo, req, query):
-    protohandler = orig(repo, req, query)
-    olddispatch = protohandler['dispatch']
+if wireprotoserver is not None:
+    # reinstall dispatch catching ResponseError as in hg 4.5 <
+    @eh.wrapfunction(wireprotoserver, 'parsehttprequest')
+    def parsehttprequest(orig, repo, req, query):
+        protohandler = orig(repo, req, query)
+        olddispatch = protohandler['dispatch']
 
-    def newdispatch():
-        try:
-            return olddispatch()
-        except hgwebcommon.ErrorResponse as inst:
-            if protohandler['cmd'] != 'listkeys':
-                raise
-            req.headers.append((r'Connection', r'Close'))
-            req.respond(inst, wireprotoserver.HGTYPE,
-                        body='0\n%s\n' % inst)
-            return ''
+        def newdispatch():
+            try:
+                return olddispatch()
+            except hgwebcommon.ErrorResponse as inst:
+                if protohandler['cmd'] != 'listkeys':
+                    raise
+                req.headers.append((r'Connection', r'Close'))
+                req.respond(inst, wireprotoserver.HGTYPE,
+                            body='0\n%s\n' % inst)
+                return ''
 
-    protohandler['dispatch'] = newdispatch
-    return protohandler
+        protohandler['dispatch'] = newdispatch
+        return protohandler
 
 @eh.uisetup
 def setuppushkeyforbidding(ui):