Fix where the error is raised, it should only be in the codepath that…

… is used when using system python

easybuild/easyblocks/generic/pythonbundle.py

@@ -111,19 +111,16 @@ def prepare_step(self, *args, **kwargs):
 
             python_cmd = pick_python_cmd(req_maj_ver=req_py_majver, req_min_ver=req_py_minver)
 
-        if python_cmd:
-            self.log.info("Python command being used: %s", python_cmd)
-        else:
-            if req_py_majver is not None or req_py_minver is not None:
+            # If pick_python_cmd didn't find a (system) python command, we should raise an error
+            if python_cmd:
+                self.log.info("Python command being used: %s", python_cmd)
+            else:
                 raise EasyBuildError(
                     "Failed to pick python command that satisfies requirements in the EasyConfigs "
                     "(req_py_majver = %s, req_py_minver = %s)", req_py_majver, req_py_minver
                 )
-            else:
-                raise EasyBuildError("Failed to pick Python command to use")
 
-        if python_cmd:
-            self.all_pylibdirs = get_pylibdirs(python_cmd=python_cmd)
+        self.all_pylibdirs = get_pylibdirs(python_cmd=python_cmd)
             self.pylibdir = self.all_pylibdirs[0]
 
         # if 'python' is not used, we need to take that into account in the extensions filter