if LooseVersion(self.version) >= "3.9.1":
    orig_ld_config_call = "with subprocess.Popen(['/sbin/ldconfig', '-p'],"
if orig_ld_config_call:

This code will crash when the Python version to be installed is less than 3.9.1 as the variable is unbound/unset in that case.
Fix is trivial: Remove the line of the 2nd if as this is the only place where the variable is set

I included 2 other changes suggested by PyLint:

• Use dict.items instead of iterating over keys and then requesting values
• Combine nested (single) ifs to remove one level of indentation at the cost of a longer condition

I can remove one or both again but IMO they make sense. At least the former which doesn't has any drawbacks I can see