Version: develop, with phpactor/phpunit-extension.

To reproduce, you can use the example from:
https://github.com/przepompownia/phpactor-bug-shared-namespace

• open src/Domain/Example.php
• :call phpactor#Navigate(), select test
  The first dialog looks correctly:
  File "tests/Domain/ExampleTest.php" does not exist, generate new?:
  After confirm I get the message:
  Error from Phpactor: File "/tmp/phpactor-shared-namespace/src/Domain/Example.php" already exists and is non-empty.