Merge branch 'fc/completion-tests'

By Felipe Contreras (4) and others * fc/completion-tests: completion: fix completion after 'git --option <TAB>' completion: avoid trailing space for --exec-path completion: add missing general options completion: simplify by using $prev completion: simplify __gitcomp_1 tests: add tests for the __gitcomp() completion helper function tests: add initial bash completion tests