Fix phase2 failures and improve QA

[ynezz]

Due to the stray ) in commit f0faed2970dd ("phase2: compute checksums") we have currently we've failing checksum step in phase2:

cd bin/packages/mipsel_24kc_24kf; find . -type f -not -name 'sha256sums' -printf "%P
" | sort | xargs -r ../../../staging_dir/host/bin/mkhash -n sha256 | sed -ne 's!^\(.*\) \(.*\)$!
 *!p' > sha256sums)
 in dir /builder/mipsel_24kc_24kf/build/sdk (timeout 1200 secs)
 watching logfiles {}
 argv: b'cd bin/packages/mipsel_24kc_24kf; find . -type f -not -name \'sha256sums\' -printf "%P\n" | sort | xargs -r ../../../staging_dir/host/bin/mkhash -n sha256 | sed -ne \'s!^\\(.*\\) \\(.*\\)$!\x01 *\x02!p\' > sha256sums)'
 environment:
...snip...
 using PTY: False
/bin/sh: 2: Syntax error: ")" unexpected
program finished with exit code 2
elapsedTime=0.007477

so lets fix it and as well try to detect such regressions in the future by improving the QA in the CI pipeline.

It seems, that flake8 is able to spot this issues:

phase2/master.cfg:739:28: W605 invalid escape sequence '\('
phase2/master.cfg:739:32: W605 invalid escape sequence '\)'
phase2/master.cfg:739:35: W605 invalid escape sequence '\('
phase2/master.cfg:739:39: W605 invalid escape sequence '\)'

[ynezz]

It seems, that flake8 is able to spot this issues:

phase2/master.cfg:739:28: W605 invalid escape sequence '\('
phase2/master.cfg:739:32: W605 invalid escape sequence '\)'
phase2/master.cfg:739:35: W605 invalid escape sequence '\('
phase2/master.cfg:739:39: W605 invalid escape sequence '\)'

It seems I was too fast and its probably that sed-fu triggering this.

[f00b4r0]

Please don't reformat phase2 yet. It's only going to make my work harder. Let's save that for "the end" as we did on phase1. Thx

[ynezz]

@f00b4r0 can you check the proposed fixes?