Catch the exception raised with 'hg help <somethingambiguous>'.
Example: 'hg help a'
#!/bin/sh
set -e
mkdir r1
cd r1
hg init
echo a > a
hg addremove
hg commit -m "1" -d "0 0"
hg clone . ../r2
cd ../r2
hg up
echo abc > a
hg diff | sed -e "s/\(+++ [a-zA-Z0-9_/.-]*\).*/\1/" \
-e "s/\(--- [a-zA-Z0-9_/.-]*\).*/\1/"
cd ../r1
echo b > b
echo a2 > a
hg addremove
hg commit -m "2" -d "0 0"
cd ../r2
hg -q pull ../r1
hg status
hg --debug up
hg --debug up -m
hg parents
hg -v history
hg diff | sed -e "s/\(+++ [a-zA-Z0-9_/.-]*\).*/\1/" \
-e "s/\(--- [a-zA-Z0-9_/.-]*\).*/\1/"