[WIP] Save db dumps for test failures

[gpetretto]

To ease the debugging of failing tests, with this PR a dump of the DB is done for each test that fails. In case the tests are running in CI the dump is uploaded to github as an artifact for inspection. This, with the content of queue.out and queue.err stored in the DB (#234), should hopefully solve #220.

A test contains a fake failure to check if the upload of the artifact is working correctly.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.21%. Comparing base (4777da6) to head (6439f4c).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #237      +/-   ##
===========================================
+ Coverage    71.16%   71.21%   +0.04%     
===========================================
  Files           50       50              
  Lines         6749     6749              
  Branches      1083     1083              
===========================================
+ Hits          4803     4806       +3     
+ Misses        1581     1576       -5     
- Partials       365      367       +2     

see 4 files with indirect coverage changes

[gpetretto]

The procedure seems to work properly. Removed the fake test failure.

[davidwaroquiers]

Sounds good to me except for the printing of the path. But maybe I am misled (and you actually did some tests so I guess it actually worked ? Not sure why the print is shown in that case though). Feel free to merge if my comments on these prints were wrong.