Convert quiet to a context manager, so its comment is no longer complaining and to simplify the code.
Remove unused import
est_manifest_is_written_with_utf8_encoding should use the filelist's append, NOT filelist.files.append

--HG--
extra : rebase_source : cdf0df0a11b96a60c29c10483579e6e043a7fcd1
Must create files for tests, else they are remoed from manifests

--HG--
extra : rebase_source : c22b55cde69bbf7fc6a075bcd8797017797c6225
Must create files for tests, else they are remoed from manifests