Instantiating datetime object with a month of 08 or 09 fails with "SyntaxError: invalid token"

Code to reproduce

import datetime

# These work
datetime.datetime(2018, 07, 01, 01, 01, 01)
datetime.datetime(2018, 8, 01, 01, 01, 01)
datetime.datetime(2018, 9, 01, 01, 01, 01)
datetime.datetime(2018, 10, 01, 01, 01, 01)

# These fail
datetime.datetime(2018, 08, 01, 01, 01, 01)
datetime.datetime(2018, 09, 01, 01, 01, 01)

Stack trace

C:\Python27\python2.exe "C:\Program Files\JetBrains\PyCharm Community Edition 2018.1.4\helpers\pydev\pydevd.py" --multiproc --qt-support=auto --client 127.0.0.1 --port 54726 --file C:/x/scripts/pycharm_issue/pycharm_issue.py
pydev debugger: process 11300 is connecting

Connected to pydev debugger (build 182.3911.33)
Traceback (most recent call last):
File "C:\Program Files\JetBrains\PyCharm Community Edition 2018.1.4\helpers\pydev\pydevd.py", line 1664, in <module>
main()
File "C:\Program Files\JetBrains\PyCharm Community Edition 2018.1.4\helpers\pydev\pydevd.py", line 1658, in main
globals = debugger.run(setup['file'], None, None, is_module)
File "C:\Program Files\JetBrains\PyCharm Community Edition 2018.1.4\helpers\pydev\pydevd.py", line 1068, in run
pydev_imports.execfile(file, globals, locals) # execute the script
File "C:/x/scripts/pycharm_issue/pycharm_issue.py", line 10
datetime.datetime(2018, 08, 01, 01, 01, 01)
^
SyntaxError: invalid token

Process finished with exit code -1

Software versions being used

PyCharm 2018.2.1 (Community Edition)
Build #PC-182.3911.33, built on August 5, 2018
JRE: 1.8.0_152-release-1248-b8 amd64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Windows 10 10.0
Project Interpreter: Python 2.7