Unresolved import for builtin packages (Python 2.7) #5881

Environment data

• VS Code version: 1.34.0
• Extension version (available under the Extensions sidebar): 2019.5
• OS and version: Windows 7
• Python version (& distribution if applicable, e.g. Anaconda): 2.7
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): N/A
• Relevant/affected Python packages and their versions: N/A

Expected behaviour

No errors for builtin packages.

Actual behaviour

Import of builtin packages like time, itertools and operator are sometimes marked as unresolved import.

Steps to reproduce:

Don't know, this happens randomly.

Logs

Starting Microsoft Python language server.
##########Linting Output - flake8##########
[Info  - 12:19:26] GetCurrentSearchPaths C:\Python27\python.exe 
[Info  - 12:19:26] Python search paths:
[Info  - 12:19:26]     c:\python27\dlls
[Info  - 12:19:26]     c:\python27\lib
[Info  - 12:19:26]     c:\python27\lib\lib-tk
[Info  - 12:19:26]     c:\python27
[Info  - 12:19:26]     c:\python27\lib\site-packages
[Info  - 12:19:26] Configuration search paths:
[Info  - 12:19:26]     ...
[Info  - 12:19:33] Microsoft Python Language Server version 0.2.87.0
[Info  - 12:19:33] Initializing for C:\Python27\python.exe

(Right now, I don't have a Console Log in case of this error. I will submit them as soon as this happens again.)