Fix tests with Python 3.9, closes PyCQA#549

Stop allowing failures on Python nightly.

.travis.yml

@@ -12,12 +12,7 @@ matrix:
       dist: xenial
     - python: 3.8
       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
+    - python: 3.9-dev
       dist: xenial
 install: pip install tox
 script: tox -e py

pyflakes/test/test_api.py

@@ -449,8 +449,6 @@ 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'
 
@@ -517,6 +515,8 @@ def foo(bar=baz, bax):
             if ERROR_HAS_LAST_LINE:
                 if PYPY:
                     column = 7
+                elif sys.version_info >= (3, 9):
+                    column = 21
                 elif sys.version_info >= (3, 8):
                     column = 9
                 else:
@@ -545,6 +545,8 @@ def test_nonKeywordAfterKeywordSyntaxError(self):
             if ERROR_HAS_LAST_LINE:
                 if PYPY:
                     column = 12
+                elif sys.version_info >= (3, 9):
+                    column = 17
                 elif sys.version_info >= (3, 8):
                     column = 14
                 else:
@@ -579,6 +581,8 @@ def test_invalidEscape(self):
                 position_end = 1
                 if PYPY:
                     column = 5
+                elif ver >= (3, 9):
+                    column = 13
                 else:
                     column = 7
                     # Column has been "fixed" since 3.2.4 and 3.3.1