fix: "already activated" message but shell is not active

[kenttonino]

Summary

• Fixes Poetry shell command does not start shell #21
• If we have a newly created shell, then deactivate, then activate the shell again, it will only show a message that Virtual environment already activated, but its not activated.
  • The problem is that we only check if the POETRY_ACTIVE is set, but not the VIRTUAL_ENV.

Changes

• command.py:
  • If the POETRY_ACTIVE is set but not the VIRTUAL_ENV, pop the POETRY_ACTIVE.

Test Plan

Test 1

• Create shell.
• Deactivate the shell.
• Activate again the shell.
  • It should activate the shell.

Test 2

• Activate the shell.
• Then, activate again.
  • It should show Virtual environment already activated.