Comment 7 for bug 1820055

In the following build:

https://github.com/brlin-tw/snapcrafters-template-plus/actions/runs/3211397149/jobs/5249538457#step:3:1190

```
The interpreter 'bash' for 'bin/my-awesome-app' was resolved to '/bin/bash'.
The command 'bin/my-awesome-app' has been changed to '/bin/bash $SNAP/bin/my-awesome-app' to safely account for the interpreter.
Failed to generate snap metadata: The specified command '/bin/bash $SNAP/bin/my-awesome-app' defined in the app 'my-awesome-app' does not match the pattern expected by snapd.
The command must consist only of alphanumeric characters, spaces, and the following special characters: / . _ # : $ -
```

The command that triggers the error is "/bin/bash $SNAP/bin/my-awesome-app", which doesn't have any of the offending characters at all. There is a problem with the logic determining whether the command is acceptable.