Don't break socket connections for postgres

[sur5r]

Also, use dict.get() for default values.

Description

Fixes #490.

#521 prevents users from setting host to an empty string for socket connections. It also contradicts the Django docs referenced in #520 which clearly state that empty HOST for Postgres means local socket connections.

Checklist

Please update this checklist as you complete each item:

• Tests have been developed for bug fixes or new functionality.
• The changelog has been updated, if necessary.
• Documentation has been updated, if necessary.
• GitHub Issues closed by this PR have been linked.

_{By submitting this pull request I agree that all contributions comply with this project's open source license(s).}

[sur5r]

This is odd. The test failures seem unrelated to the changes.

[Archmonger]

It does seem to somehow be related to this PR's changes.

Just rebased #536 and got no CI errors.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.44%. Comparing base (8f1307e) to head (25a4bb7).
Report is 18 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #540      +/-   ##
==========================================
+ Coverage   91.40%   91.44%   +0.03%     
==========================================
  Files          19       19              
  Lines         873      912      +39     
  Branches      157      154       -3     
==========================================
+ Hits          798      834      +36     
- Misses         40       43       +3     
  Partials       35       35              

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[sur5r]

I got confused by the sqlite errors, but those seem to be expected/ok.

I couldn't track down the problem completely, but there seems to be some modification of the USER setting that breaks the interaction with get() and a default value.

At some point during the tests, self.settings.get("USER","") returns None which could only happen if None was assigned explicitely. I couldn't find that place in the code, though.

[Archmonger]

Could be this LOC, not sure though

https://github.com/jazzband/django-dbbackup/blob/master/dbbackup%2Ftests%2Ftest_connectors%2Ftest_postgresql.py#L49

[Archmonger]

Will go ahead and merge this since it's a step up from current behavior. If someone in the future needs self.settings.get("USER","") then they will need to debug it within their PR.