[PATCH 1 of 2 evolve-ext v2] evolve: make split respect rev args passed without --rev or -r

[Kostia Balytskyi]

# HG changeset patch
# User Kostia Balytskyi <ikostia at fb.com>
# Date 1454321971 28800
#      Mon Feb 01 02:19:31 2016 -0800
# Node ID 8cf256f9050bca9c6ff190bf732e9ce687818d5f
# Parent  983f2e4dbe5d4d97d6ca82f6679913d75c1f2577
evolve: make split respect rev args passed without --rev or -r

Currently, if one runs `hg split .` or `hg split`, it will fail
with an exception. This happens becuase we only expect revision
args to be passed as --rev/-r ones and don't treat unnamed args
properly or add default values if no args are provided.

diff --git a/hgext/evolve.py b/hgext/evolve.py
--- a/hgext/evolve.py
+++ b/hgext/evolve.py
@@ -2729,15 +2729,12 @@
     tr = wlock = lock = None
     newcommits = []
 
-    revopt = opts.get('rev')
-    if revopt:
-        revs = scmutil.revrange(repo, revopt)
-        if len(revs) != 1:
-            raise error.Abort(_("you can only specify one revision to split"))
-        else:
-            rev = list(revs)[0]
+    revarg = revs or opts.get('rev') or '.'
+    revs = scmutil.revrange(repo, revarg)
+    if len(revs) != 1:
+        raise error.Abort(_("you can only specify one revision to split"))
     else:
-        rev = '.'
+        rev = list(revs)[0]
 
     try:
         wlock = repo.wlock()