check-code: add check for lock release order

parsers: fix variable declaration position issue

zsh_completion: complete all files for `commit/backout --logfile` Up until now commit/backout `--logfile` option was completed only with *.txt-files. This requirement is a bit too strong (and is nowhere to be stated) so it's better to complete with all files. Stolen from zsh.git repo, c5fce37b changeset by Oliver Kiddle.

transplant: improve documentation

transplant: clarify what --branch do - it has nothing to do with branches --branch specifies heads and has nothing to do with named branches, and it only deals with topological branches to the same extent as all other DAG operations do.

import: inline checkexact function We have a sngle call now, no need to make it a function.

import: factor out checkexact The two calls are strictly identical. We can simply move it after the if/else clause.

amend: fix unlocking order - first lock then wlock

codingstyle: remove trailing spaces in various text files Better do it once than see random changes in diffs later.

tests: run check-code on Python files without .py extension