`gh-clone': not a valid identifier when running 'source common_utils.sh' as root on MacOS

[ogarod]

On MacOS, attempting to 'source' a bash script under the root user fails if it has function names with hyphens. Running source common_utils.sh as root after checking out this repository on Mojave and High Sierra fails with the following error:

common_utils.sh: line 94: `gh-clone': not a valid identifier

Hyphens should not be used in function names, so the error message sort of makes sense: https://stackoverflow.com/questions/28114999/what-are-the-rules-for-valid-identifiers-e-g-functions-vars-etc-in-bash

[matthew-brett]

Fair enough - any interest in a pull request?