Merge branch 'sg/test-i18ngrep'

Test fixes. * sg/test-i18ngrep: t: make 'test_i18ngrep' more informative on failure t: validate 'test_i18ngrep's parameters t: move 'test_i18ncmp' and 'test_i18ngrep' to 'test-lib-functions.sh' t5536: let 'test_i18ngrep' read the file without redirection t5510: consolidate 'grep' and 'test_i18ngrep' patterns t4001: don't run 'git status' upstream of a pipe t6022: don't run 'git merge' upstream of a pipe t5812: add 'test_i18ngrep's missing filename parameter t5541: add 'test_i18ngrep's missing filename parameter