run-tests.py: pass -L/--label to simplemerge
This should give us conflict markers that don't change from one run
to another.
Remove some sed's/egrep's from some tests.
*** failed to import extension badext: bit bucket overflowextension 'hgext.gpg' overrides commands: sigs sigcheck signhg help [COMMAND]show help for a command, extension, or list of commands