simplify code for determining the PYTHONPAH module entries

The check whether the path(s) have already been added is redundant as that is done in the module_generator class.

The whole code with all the checks is superflous if there are no python paths to add.

To avoid excessive indentation return early with an empty list in that case and same for Python installations for consistency.

easybuild/framework/easyblock.py

@@ -1399,43 +1399,40 @@ def make_module_pythonpath(self):
         Add lines for module file to update $PYTHONPATH or $EBPYTHONPREFIXES,
         if they aren't already present and the standard lib/python*/site-packages subdirectory exists
         """
-        lines = []
-        if not os.path.isfile(os.path.join(self.installdir, 'bin', 'python')):  # only needed when not a python install
-            python_subdir_pattern = os.path.join(self.installdir, 'lib', 'python*', 'site-packages')
-            candidate_paths = (os.path.relpath(path, self.installdir) for path in glob.glob(python_subdir_pattern))
-            python_paths = [path for path in candidate_paths if re.match(r'lib/python\d+\.\d+/site-packages', path)]
+        if os.path.isfile(os.path.join(self.installdir, 'bin', 'python')):  # only needed when not a python install
+            return []
 
-            # determine whether Python is a runtime dependency;
-            # if so, we assume it was installed with EasyBuild, and hence is aware of $EBPYTHONPREFIXES
-            runtime_deps = [dep['name'] for dep in self.cfg.dependencies(runtime_only=True)]
+        python_subdir_pattern = os.path.join(self.installdir, 'lib', 'python*', 'site-packages')
+        candidate_paths = (os.path.relpath(path, self.installdir) for path in glob.glob(python_subdir_pattern))
+        python_paths = [path for path in candidate_paths if re.match(r'lib/python\d+\.\d+/site-packages', path)]
+        if not python_paths:
+            return []
 
-            # don't use $EBPYTHONPREFIXES unless we can and it's preferred or necesary (due to use of multi_deps)
-            use_ebpythonprefixes = False
-            multi_deps = self.cfg['multi_deps']
+        # determine whether Python is a runtime dependency;
+        # if so, we assume it was installed with EasyBuild, and hence is aware of $EBPYTHONPREFIXES
+        runtime_deps = [dep['name'] for dep in self.cfg.dependencies(runtime_only=True)]
 
-            if 'Python' in runtime_deps:
-                self.log.info("Found Python runtime dependency, so considering $EBPYTHONPREFIXES...")
+        # don't use $EBPYTHONPREFIXES unless we can and it's preferred or necesary (due to use of multi_deps)
+        use_ebpythonprefixes = False
+        multi_deps = self.cfg['multi_deps']
 
-                if build_option('prefer_python_search_path') == EBPYTHONPREFIXES:
-                    self.log.info("Preferred Python search path is $EBPYTHONPREFIXES, so using that")
-                    use_ebpythonprefixes = True
+        if 'Python' in runtime_deps:
+            self.log.info("Found Python runtime dependency, so considering $EBPYTHONPREFIXES...")
 
-            elif multi_deps and 'Python' in multi_deps:
-                self.log.info("Python is listed in 'multi_deps', so using $EBPYTHONPREFIXES instead of $PYTHONPATH")
+            if build_option('prefer_python_search_path') == EBPYTHONPREFIXES:
+                self.log.info("Preferred Python search path is $EBPYTHONPREFIXES, so using that")
                 use_ebpythonprefixes = True
 
-            if python_paths:
-                # add paths unless they were already added
-                if use_ebpythonprefixes:
-                    path = ''  # EBPYTHONPREFIXES are relative to the install dir
-                    if path not in self.module_generator.added_paths_per_key[EBPYTHONPREFIXES]:
-                        lines.append(self.module_generator.prepend_paths(EBPYTHONPREFIXES, path))
-                else:
-                    for python_path in python_paths:
-                        if python_path not in self.module_generator.added_paths_per_key[PYTHONPATH]:
-                            lines.append(self.module_generator.prepend_paths(PYTHONPATH, python_path))
+        elif multi_deps and 'Python' in multi_deps:
+            self.log.info("Python is listed in 'multi_deps', so using $EBPYTHONPREFIXES instead of $PYTHONPATH")
+            use_ebpythonprefixes = True
 
-        return lines
+        if use_ebpythonprefixes:
+            path = ''  # EBPYTHONPREFIXES are relative to the install dir
+            lines = self.module_generator.prepend_paths(EBPYTHONPREFIXES, path)
+        else:
+            lines = self.module_generator.prepend_paths(PYTHONPATH, python_paths)
+        return [lines] if lines else []
 
     def make_module_extra(self, altroot=None, altversion=None):
         """