Merge branch 'ab/test-lib'

Test framework clean-up. * ab/test-lib: test-lib-functions: assert correct parameter count test-lib-functions: remove bug-inducing "diagnostics" helper param test libs: rename "diff-lib" to "lib-diff" t/.gitattributes: sort lines test-lib-functions: move function to lib-bitmap.sh test libs: rename gitweb-lib.sh to lib-gitweb.sh test libs: rename bundle helper to "lib-bundle.sh" test-lib-functions: remove generate_zero_bytes() wrapper test-lib-functions: move test_set_index_version() to its user test lib: change "error" to "BUG" as appropriate test-lib: remove check_var_migration