Remove installation scheme tweaking hack.

It was needed on older Debians.

It breaks new Debian.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1020567

run_meson_command_tests.py

diff --git a/run_meson_command_tests.py b/run_meson_command_tests.py
index 03083f0..6d8aae1 100755
--- a/run_meson_command_tests.py
+++ b/run_meson_command_tests.py
@@ -31,8 +31,6 @@
     scheme = sysconfig.get_default_scheme()
 else:
     scheme = sysconfig._get_default_scheme()
-if scheme == 'posix_local':
-    scheme = 'posix_prefix'
 
 def get_pypath():
     pypath = sysconfig.get_path('purelib', scheme=scheme, vars={'base': ''})