ReFrame fails with Tcl versions that use modulecmd.tcl as executable

[rsarm]

ReFrame checks for the module system by running the modulecmd command.

Some versions of Tcl do not have the modulecmd binary. Instead they use the script ~/libexec/modulecmd.tcl which is used by the module function in a similar way to modulecmd. They can not be replaced between each other, doing a symlink from modulecmd.tcl to modulecmd doesn't work as ReFrame gives configuration error: could not find a sane Tmod installation.

The details of the module function can be found with type -a _moduleraw. In the cases where the modulecmd.tcl is used, module depends on another function: _moduleraw. With type -a _moduleraw it can be seen that it used libexec/modulecmd.tcl.

[vkarak]

I don't think that it's safe to inspect the bash functions so as to retrieve the path of the modulecmd. We need modulecmd to be in path, cos this provides us the Python bindings. Of course, we can expand the backend to look for modulecmd.tcl if modulecmd is not found. We could also fine tune the error message, so that we instruct the user that we need modulecmd in the PATH. Documentation should also be updated.

[vkarak]

As discussed offline and in #781, it seems that we don't support Tmod prior to 3.2 and Tmod 4.1.