Clarified message when nothing to merge is seen. Sometimes there's a non-tip head waiting to be merged, especially after pulling in remote changes while there were local modifications in the working directory which had to be committed before 'hg merge' can work.

#!/bin/sh

hg init a
echo a > a/a
hg --cwd a ci -A -m a
hg clone a b
echo b > b/b
hg --cwd b ci -A -m b
chmod 100 a/.hg
hg --cwd b push ../a
chmod 700 a/.hg