scmutil: introduce deprecated alias for revpair()

revsingle() returns a context object, revpair() returns nodeids,
revrange() returns integer revisions (in a revset). I'm going to
reduce this inconsistency by making revpair() return context
objects. Changing the return type is not nice to extensions, so this
patch introduces a nodeid-returning version of revpair() that they can
detect and use. Update callers to the new function so we can change
revpair() itself and then migrate them back one by one.

Differential Revision: https://phab.mercurial-scm.org/D3005

hgext/extdiff.py

@@ -171,7 +171,7 b' def dodiff(ui, repo, cmdline, pats, opts'
         node2 = scmutil.revsingle(repo, change, None).node()
         node1a, node1b = repo.changelog.parents(node2)
     else:
-        node1a, node2 = scmutil.revpair(repo, revs)
+        node1a, node2 = scmutil.revpairnodes(repo, revs)
         if not revs:
             node1b = repo.dirstate.p2()
         else:

mercurial/commands.py

@@ -1878,7 +1878,7 b' def diff(ui, repo, *pats, **opts):'
         node1 = repo[node2].p1().node()
     else:
         repo = scmutil.unhidehashlikerevs(repo, revs, 'nowarn')
-        node1, node2 = scmutil.revpair(repo, revs)
+        node1, node2 = scmutil.revpairnodes(repo, revs)
 
     if reverse:
         node1, node2 = node2, node1
@@ -4880,7 +4880,7 b' def status(ui, repo, *pats, **opts):'
         node1 = repo[node2].p1().node()
     else:
         repo = scmutil.unhidehashlikerevs(repo, revs, 'nowarn')
-        node1, node2 = scmutil.revpair(repo, revs)
+        node1, node2 = scmutil.revpairnodes(repo, revs)
 
     if pats or ui.configbool('commands', 'status.relative'):
         cwd = repo.getcwd()

mercurial/fileset.py

@@ -513,7 +513,7 b' def status(mctx, x):'
     revspec = getstring(r, reverr)
     if not revspec:
         raise error.ParseError(reverr)
-    basenode, node = scmutil.revpair(repo, [baserevspec, revspec])
+    basenode, node = scmutil.revpairnodes(repo, [baserevspec, revspec])
     basectx = repo[basenode]
     ctx = repo[node]
     return getset(mctx.switch(ctx, _buildstatus(ctx, x, basectx=basectx)), x)

mercurial/scmutil.py

@@ -446,6 +446,9 b' def _pairspec(revspec):'
     tree = revsetlang.parse(revspec)
     return tree and tree[0] in ('range', 'rangepre', 'rangepost', 'rangeall')
 
+def revpairnodes(repo, revs):
+    return revpair(repo, revs)
+
 def revpair(repo, revs):
     if not revs:
         return repo.dirstate.p1(), None

tests/autodiff.py

@@ -40,7 +40,7 b' def autodiff(ui, repo, *pats, **opts):'
     else:
         raise error.Abort(b'--git must be yes, no or auto')
 
-    node1, node2 = scmutil.revpair(repo, [])
+    node1, node2 = scmutil.revpairnodes(repo, [])
     m = scmutil.match(repo[node2], pats, opts)
     it = patch.diff(repo, node1, node2, match=m, opts=diffopts,
                     losedatafn=losedatafn)