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