small fixes for test-newbranch - hg tip doesn't use the branch cache; use hg log -r in its place - commit doesn't use a HG_MERGE environment variable - change the dates from "0 0" to "1000000 0"

#!/bin/sh
# http://www.selenic.com/mercurial/bts/issue433

hg init a
cd a       
echo a > a 
hg commit -Ama 

hg parents -r 0 doesnotexist
true