revset-node: speedup by a few hundred fold

Instead of checking all elements of the subset against a single rev, just check
if this rev is in the subset. The old way was inherited from when the subset was
a list.

Non surprise, this provide massive speedup.


id("d82e2223f132")
before) wall 0.008205 comb 0.000000 user 0.000000 sys 0.000000 (best of 302)
after)  wall 0.000069 comb 0.000000 user 0.000000 sys 0.000000 (best of 34518)

revset  #1: public() and id("d82e2223f132")
before) wall 0.019763 comb 0.020000 user 0.020000 sys 0.000000 (best of 124)
after)  wall 0.000101 comb 0.000000 user 0.000000 sys 0.000000 (best of 20130)

mercurial/revset.py

@@ -1132,7 +1132,10 b' def node_(repo, subset, x):'
         if pm is not None:
             rn = repo.changelog.rev(pm)
 
-    return subset.filter(lambda r: r == rn)
+    if rn is None:
+        return baseset()
+    result = baseset([rn])
+    return result & subset
 
 def obsolete(repo, subset, x):
     """``obsolete()``