Add test for presence of python without -s

test/easyconfigs/easyconfigs.py

@@ -1181,6 +1181,19 @@ def test_pr_python_packages(self):
                 sanity_pip_check = ec.get('sanity_pip_check') or exts_default_options.get('sanity_pip_check')
                 if not sanity_pip_check and not any(re.match(regex, ec_fn) for regex in whitelist_pip_check):
                     failing_checks.append("sanity_pip_check should be enabled in %s" % ec_fn)
+            else:
+                # Make sure the user packages in $HOME/.local/lib/python*/ are ignored when running python commands
+                # For the EasyBlocks above this is handled automatically by setting $PYTHONNOUSERSITE
+                # Detect any code or module invocation (-m or -c), `python cc` and `python <filepath>`
+                python_re = re.compile(r'\bpython (-c|-m|cc|[^ ]*\w+.py) ')
+                # Detect if `-s` is present, potentially after other switches
+                ignore_user_switch_re = re.compile(r'\bpython (-\w+ )*-s ')
+                # Check the raw lines as the issue could be anywhere, not only in `sanity_check_commands`,
+                # e.g. `runtest`, `installopts`, `configopts`, ...
+                for line in read_file(ec.path).splitlines():
+                    if python_re.search(line) and not ignore_user_switch_re.search(line):
+                        failing_checks.append("Python invocation in '%s' should use the '-s' parameter in %s"
+                                              % (line, ec_fn))
 
         if failing_checks:
             self.fail('\n'.join(failing_checks))