Fix issue described in #11421

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11421
| License       | MIT
| Doc PR        | NA

This pull request fixes the issue described in #11421.  It also adds a test for the issue.  The issue is present in 2.0 forward, but I decided to fix it on the 2.3 branch so that I could also write a test for it (2.0 had no tests for the Process component, and 2.1 and 2.2 didn't have tests for the `ExecutableFinder` class).
You can use a `/` here instead of `DIRECTORY_SEPARATOR`