revset: map postfix '%' to only() to optimize operand recursively (issue4670)

Instead of keeping 'onlypost' as a method, this patch rewrites it to 'only'
function. This way, 'x%' always has the same weight as 'only(x)'.

mercurial/revset.py

@@ -2098,7 +2098,6 b' methods = {'
     "parent": parentspec,
     "parentpost": p1,
     "only": only,
-    "onlypost": only,
 }
 
 def optimize(x, small):
@@ -2115,6 +2114,8 b' def optimize(x, small):'
     elif op == 'only':
         return optimize(('func', ('symbol', 'only'),
                          ('list', x[1], x[2])), small)
+    elif op == 'onlypost':
+        return optimize(('func', ('symbol', 'only'), x[1]), small)
     elif op == 'dagrangepre':
         return optimize(('func', ('symbol', 'ancestors'), x[1]), small)
     elif op == 'dagrangepost':

tests/test-revset.t

@@ -533,6 +533,29 b" Test '%' operator"
   8
   9
 
+Test opreand of '%' is optimized recursively (issue4670)
+
+  $ try --optimize '8:9-8%'
+  (onlypost
+    (minus
+      (range
+        ('symbol', '8')
+        ('symbol', '9'))
+      ('symbol', '8')))
+  * optimized:
+  (func
+    ('symbol', 'only')
+    (and
+      (range
+        ('symbol', '8')
+        ('symbol', '9'))
+      (not
+        ('symbol', '8'))))
+  * set:
+  <baseset+ [8, 9]>
+  8
+  9
+
 Test the order of operations
 
   $ log '7 + 9%5 + 2'