The documentation for the version_command tag doesn't mention it can take an interpreter option:
https://wiki.galaxyproject.org/Admin/Tools/ToolConfigSyntax#A.3Cversion_command.3E_tag_set

I looked at the code in lib/galaxy/tools/__init__.py to see how this was implemented. I was surprised to see that if the interpreter option is passed to version_command, then the interpreter value from the command tag is used in generating the version number response. The version_command interpreter value is never used. For example, I tried the following:

<version_command interpreter="foobar">myPythonTool -v</version_command>

<command interpreter="python">myPythonTool someCheetahCode</command>

And Galaxy successfully got the version number. Is this the expected behavior?

-Will