test: use `hg log` in the `getid` function using `hg id` to retrieve full lenght node requires to use --debug. This may include debug output (regarding branch cache invalidation for example) that breaks the test. We now use `hg log` with a custom template. This is a simple, clean and robust solution.

readme: mention patchbomb usage and patch description guidelines on wiki

debian: add line to clean target to delete error files caused by failing tests