merge: fix --preview to show all nodes that will be merged (issue2043).
Formerly, it omitted nodes that were not descendants of the least
common ancestor of the two merge parents, even though those nodes
contribute to the merge. The new algorithm uses revlog.findmissing()
instead of ancestor() + nodesbetween().
#!/usr/bin/env python
import sys, os
from mercurial import revlog, transaction, node, util
f = sys.argv[1]
r1 = revlog.revlog(util.opener(os.getcwd(), audit=False), f + ".i", f + ".d")
r2 = revlog.revlog(util.opener(os.getcwd(), audit=False), f + ".i2", f + ".d2")
tr = transaction.transaction(sys.stderr.write, open, "journal")
for i in xrange(r1.count()):
n = r1.node(i)
p1, p2 = r1.parents(n)
l = r1.linkrev(n)
t = r1.revision(n)
n2 = r2.addrevision(t, tr, l, p1, p2)
tr.close()
os.rename(f + ".i", f + ".i.old")
os.rename(f + ".d", f + ".d.old")
os.rename(f + ".i2", f + ".i")
os.rename(f + ".d2", f + ".d")