There was a bug where if git was not installed then gh would do its
authentication and try to configure git but would then find out that the
git executable was not in PATH.
Now gh checks to see if the git executable is in PATH before
authenticating the user. If the git executable is in PATH the
authentication continues as normal, if it is not in PATH then it prints
out an error to the console:
$ git executable not found in $PATH
Resolves: #3818
e28236a447