tests/test-1102

extensions: move extensions listing functions from mercurial.help

Includes some small fix-ups to comments in enabled() and disabled().

#!/bin/sh

rm -rf a
hg init a
cd a
echo a > a
hg ci -Am0
hg tag t1 # 1
hg tag --remove t1 # 2

hg co 1
hg tag -r0 t1
hg tags