pac solution sync does not bring down environment variables into the source

[scottdurow]

Describe the bug
When using pac solution sync, environments are not always synced and missing from the solution unpacked source.

This may be related to #477

To Reproduce
Steps to reproduce the behavior:

1. Create an empty solution
2. Clone the solution using pac solution clone
3. Add a new string environment variable to the solution.
4. Sync the solution using pac solution sync - the string environment will be synced
5. Add a Boolean (Yes/No) environment variable
6. Sync the solution again using pac solution sync - the bool environment is not present in the solution source
7. Repeat Steps 5 and 6 until the issue happens - it sometimes seems to sync and sometimes doesn't.

Expected behavior
Environment variables should always be synced correctly.

Additional context
Using version 1.33.5+g1621296 of PAC