non-interactive merge

[TK Soh]

I am adding a simple merge support to tortoisehg. Basically just a
popen to 'hg merge', and file merge is handled by simplemerge (thanks
to asak ;-).  I wonder how hg merge handles conflicts on file
creation/deletion, when running in non-interactive mode. IIRC, hg
merge would prompt for user to decide what actions are to be taken,
but this would break my current simple approach. Any comment?