UPM log file end up in the previously opened project instead of the currently opened project

Steps to reproduce:

• Open ProjectA in Unity
• Close ProjectA and open ProjectB
• Inspect <ProjectPath>/Logs/upm.log in ProjectA/ and ProjectB/

Actual results: 

UPM logs are consistently written to the previously opened project's Logs/ directory. In this case, logs are in under ProjectA's directory.

Expected results: 

When opening ProjectB, UPM logs should be written to <ProjectB>/Logs/upm.log.
Switching to any project should always produce logs under that project's own Logs/ folder, regardless of which project was opened previously in the same Editor session.

Reproducible with versions: 

6000.6.0a2 and 6000.5.0a8

Tested on (OS): 

macOS and Windows