avoid using sys.modules.clear() in tests

Author: boegel

test/framework/options.py

@@ -3047,7 +3047,6 @@ def test_xxx_include_easyblocks_from_pr(self):
             return
 
         orig_local_sys_path = sys.path[:]
-        orig_sys_modules = sys.modules.copy()
 
         fd, dummylogfn = tempfile.mkstemp(prefix='easybuild-dummy', suffix='.log')
         os.close(fd)
@@ -3093,8 +3092,8 @@ def test_xxx_include_easyblocks_from_pr(self):
         self.assertTrue(issubclass(klass, EasyBlock), "%s is an EasyBlock derivative class" % klass)
 
         # 'undo' import of easyblocks
-        sys.modules.clear()
-        sys.modules.update(orig_sys_modules)
+        del sys.modules['easybuild.easyblocks.foo']
+        del sys.modules['easybuild.easyblocks.generic.cmakemake']
         os.remove(os.path.join(self.test_prefix, 'foo.py'))
         sys.path = orig_local_sys_path