tests/test-update-reverse

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().

#!/bin/sh

hg init
touch a
hg add a
hg commit -m "Added a" -d "1000000 0"

touch main
hg add main
hg commit -m "Added main" -d "1000000 0"
hg checkout 0

echo Main should be gone
ls

touch side1
hg add side1
hg commit -m "Added side1" -d "1000000 0"
touch side2
hg add side2
hg commit -m "Added side2" -d "1000000 0"

hg log

echo Should have two heads, side2 and main
hg heads

echo Should show "a side1 side2"
ls

hg update --debug -C 1
echo Should only show "a main"
ls