changegroup: introduce an explicit linear sorting

We still need to linearize the revisions in some cases, introduce an explicit
`linear` sorting before changing back the default order.

Differential Revision: https://phab.mercurial-scm.org/D5195

hgext/sqlitestore.py

@@ -559,7 +559,7 b' class sqlitefilestore(object):'
 
     def emitrevisions(self, nodes, nodesorder=None, revisiondata=False,
                       assumehaveparentrevisions=False, deltaprevious=False):
-        if nodesorder not in ('nodes', 'storage', None):
+        if nodesorder not in ('nodes', 'storage', 'linear', None):
             raise error.ProgrammingError('unhandled value for nodesorder: %s' %
                                          nodesorder)
 

mercurial/revlog.py

@@ -2206,7 +2206,7 b' class revlog(object):'
 
     def emitrevisions(self, nodes, nodesorder=None, revisiondata=False,
                       assumehaveparentrevisions=False, deltaprevious=False):
-        if nodesorder not in ('nodes', 'storage', None):
+        if nodesorder not in ('nodes', 'storage', 'linear', None):
             raise error.ProgrammingError('unhandled value for nodesorder: %s' %
                                          nodesorder)