Fixes for pipenv activation

[DonJayamanne]

For #2855

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR)
• Title summarizes what is changing
• [n/a] Has a news entry file (remember to thank yourself!)
• [n/a] Has sufficient logging.
• [n/a] Has telemetry for enhancements.
• Unit tests & system/integration tests are added/updated
• [n/a] Test plan is updated as appropriate
• [n/a] package-lock.json has been regenerated by running npm install (if dependencies have changed)

[codecov]

Codecov Report

Merging #4105 into master will decrease coverage by 1%.
The diff coverage is 73%.

@@           Coverage Diff           @@
##           master   #4105    +/-   ##
=======================================
- Coverage      79%     79%   -<1%     
=======================================
  Files         407     407            
  Lines       18644   18733    +89     
  Branches     3007    3032    +25     
=======================================
+ Hits        14608   14669    +61     
- Misses       4033    4054    +21     
- Partials        3      10     +7

Flag	Coverage Δ
#Linux	68% <82%> (ø)	⬇️
#Windows	68% <82%> (ø)	⬇️
#macOS	68% <82%> (+1%)	⬆️