Add locking for update menus

[tim-moody]

No description provided.

[tim-moody]

testing on a large install would be welcome
passed smoke test and basic functional test

[holta]

testing on a large install would be welcome

@neomatrixcode can you possibly help?

Apparently related:

• Extra characters on the end of menu.json cause Home Page to be blank iiab#3487
  • https://github.com/iiab/iiab/issues/3487 workarounds #536
• cest-pas-sorcier_fr_top didn't appear on IIAB main page and Python JSONDecodeError iiab#3602

[tim-moody]

passed smoke test and simple function with latest changes

[holta]

@neomatrixcode can you possibly help?

This PR is likely superseded by a better one here:

• PR support full log output for selected commands #545

[neomatrixcode]

sudo iiab-diagnostics results after running the command curl iiab.io/fast.txt | bash -s 544

http://sprunge.us/FMib3p

[holta]

http://sprunge.us/FMib3p?en

Many thanks @neomatrixcode for having tested:

• LARGE-sized as @tim-moody suggested
• 169G you installed
• about 35 Content Packs you installed

Conclusion: all testing helps! But we still don't quite know what conditions bring about the iiab/iiab#3487 and iiab/iiab#3602 issues.

[tim-moody]

@neomatrixcode thanks for the big test.

I'm not seeing any errors in the diagnostics. Were any problems noticed? Does the home page look right? Is there a maps link?

[tim-moody]

Is there a reason not to merge this PR?

[holta]

Is there a reason not to merge this PR?

Feel free and/or to merge PR #545 including this one.

[tim-moody]

Problems not addressed by the PR:

• Services are either not added (OSM) or only added as EN (kalite)
• Credits is only recognized as last menu item in EN