httppeer: use %s for formatting

This prevents a b'' from appearing in Python 3 output. We keep the
single quotes for backwards compatibility.

Differential Revision: https://phab.mercurial-scm.org/D5647

mercurial/httppeer.py

@@ -816,8 +816,8 b' class httpv2peer(object):'
             return
 
         raise error.CapabilityError(
-            _('cannot %s; client or remote repository does not support the %r '
-              'capability') % (purpose, name))
+            _('cannot %s; client or remote repository does not support the '
+              '\'%s\' capability') % (purpose, name))
 
     # End of ipeercapabilities.
 

mercurial/repository.py

@@ -346,8 +346,8 b' class peer(object):'
             return
 
         raise error.CapabilityError(
-            _('cannot %s; remote repository does not support the %r '
-              'capability') % (purpose, name))
+            _('cannot %s; remote repository does not support the '
+              '\'%s\' capability') % (purpose, name))
 
 class iverifyproblem(interfaceutil.Interface):
     """Represents a problem with the integrity of the repository.