Fix push finish on racing conditions

[varmar05]

Server determines the next version on push finish just before moving files which were already prepared (including geodiff acttions). This should address the issue when during push finish another version is already created.

Workflow in push finish is changed that all hard work is done before final version check.

Example:

• on push finish server is currently on v4
• during chunks merge someone else created v5 version
• before commit to db server would bump to v6 for current push finish and move already created files to correct destination

[coveralls]

Pull Request Test Coverage Report for Build 16287797316

Details

• 63 of 67 (94.03%) changed or added relevant lines in 4 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.02%) to 91.847%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
server/mergin/sync/public_api_controller.py	47	51	92.16%

Files with Coverage Reduction	New Missed Lines	%
server/mergin/sync/public_api_controller.py	1	91.21%

Totals
Change from base Build 16074058805:	-0.02%
Covered Lines:	7221
Relevant Lines:	7862

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💛 - Coveralls

[harminius]

When running concurrent sync tests from plugin I still keep hitting the db constraint when committing the same version (see client B log). Could we reintroduce the 409 error code so that client can retry?

B_client-log.txt
A_client-log.txt

[MarcelGeo]

When running concurrent sync tests from plugin I still keep hitting the db constraint when committing the same version (see client B log). Could we reintroduce the 409 error code so that client can retry?

B_client-log.txt A_client-log.txt

I'm not sure what you think regarding to logs :) But we will rewrite some logic in sync. We need to reintroduce harder versions check to push start to prevent going to push finish with invalid versions.