record: check that we are not committing a merge before patch selection
It might sound like a good idea to use record to filter changes when merging.
If someone attemps this, it's better to tell her "no" right ahead, before the
patch generation/line selection, so she does not spend time doing it just to
receive a red light after that (sometimes rather long) process.
#!/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