Create a test for the 'database is locked' and 'database table is locked' error

[typeless]

I tried to re-use the 'NewIssue' integration test for the purpose, creating a test with two goroutines each looping the test 100 times. But it takes quite long time to run and not that reliable given the number of iterations are not that high.

Any thoughts?

[bkcsoft]

This is easy actually, just make all tests run in parallel ;)

[typeless]

@bkcsoft Would it not affect the CI running time? I suppose the Drone CI server doesn't provide too many cores for free instances.

Anyway I will still submit the PR for troubleshooting the database locking issue. And we can discuss whether to add it to the 'official' test suite later.

[bkcsoft]

Running the test in parallel would make it run faster, if we allow to run multiple processes 😉

[lunny]

testing for #2040

[lunny]

Closed by #5144 since the test-sqlite has been reenabled on that PR.