At least with ZSH, prefix inspections containing `./bin` result in a
`$PREFIX/./bin` and result in strange `$PATH` handling.
I.e., `module load git` will prepend `/path/to/git/./bin`, `which git`
will find the right executable, but `git --version` will print the
system one. Normalize the relative path to avoid this behavior.
See also spack/spack#31867.
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