Fix test for nightly Python (3.9) (#532)

* Fix test for nightly Python (3.9)

* allow_failures: true for nightly

Co-authored-by: Anthony Sottile <[email protected]>

Author: PetterS

.travis.yml

@@ -12,5 +12,10 @@ matrix:
       dist: xenial
     - python: nightly
       dist: xenial
+# TODO: https://bugs.python.org/issue40334
+# the PEG parser is currently broken in some cases
+  allow_failures:
+    - python: nightly
+      dist: xenial
 install: pip install tox
 script: tox -e py

pyflakes/test/test_api.py

@@ -449,6 +449,8 @@ def evaluate(source):
         with self.makeTempFile(source) as sourcePath:
             if PYPY:
                 message = 'end of file (EOF) while scanning triple-quoted string literal'
+            elif sys.version_info >= (3, 9):
+                message = 'invalid string prefix'
             else:
                 message = 'invalid syntax'