Python 3.7 support
The BuildStream test suite currently fails with Python 3.7 due to requiring an old version of pylint (see also #427 (closed)) and one function not conforming to PEP 479. This MR addresses these two issues.
A possible issue remaining is that astroid
pulls in the typing
package even though it's not needed with Python 3.5+ and incompatible with Python 3.7, see also https://github.com/python/typing/issues/573 Removing typing.py
works around this issue.