[enriched/git] `enrich_git_branches` skip --filter-no-collection repo

[zhquan]

This code skips the study when --filter-no-collection is present due to that repo was removed from upstream or we don't have permission.

Test added accordingly.

Signed-off-by: Quan Zhou quan@bitergia.com

[coveralls]

Pull Request Test Coverage Report for Build 2426

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 28 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.09%) to 82.285%

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Files with Coverage Reduction	New Missed Lines	%
/home/travis/build/chaoss/grimoirelab-elk/grimoire_elk/enriched/git.py	28	70.53%
<!--	Total:	28		-->

Totals
Change from base Build 2422:	0.09%
Covered Lines:	8454
Relevant Lines:	10274

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💛 - Coveralls