Fix autoload of direct dependencies for python (#9630)

fixes #9624

merge_config_rules was using `strict=False` to check if a spec
satisfies a constraint, which loosely translates to "this spec has
no conflict with the constraint, so I can potentially add it to the
spec". We want instead `strict=True` which means "the spec satisfies
the constraint right now".

lib/spack/spack/modules/common.py

@@ -173,7 +173,7 @@ def merge_config_rules(configuration, spec):
         if constraint.endswith(':'):
             constraint = constraint.strip(':')
             override = True
-        if spec.satisfies(constraint):
+        if spec.satisfies(constraint, strict=True):
             if override:
                 spec_configuration = {}
             update_dictionary_extending_lists(spec_configuration, action)

lib/spack/spack/test/data/modules/tcl/autoload_with_constraints.yaml

+enable:
+  - tcl
+tcl:
+  ^mpich2:
+    autoload: 'direct'
+
+  ^python:
+    autoload: 'direct'

lib/spack/spack/test/modules/tcl.py

@@ -276,3 +276,20 @@ def test_blacklist_implicits(
         for item in callpath_specs:
             writer = writer_cls(item)
             assert writer.conf.blacklisted
+
+    @pytest.mark.regression('9624')
+    @pytest.mark.db
+    def test_autoload_with_constraints(
+            self, modulefile_content, module_configuration, database
+    ):
+        """Tests the automatic loading of direct dependencies."""
+
+        module_configuration('autoload_with_constraints')
+
+        # Test the mpileaks that should have the autoloaded dependencies
+        content = modulefile_content('mpileaks ^mpich2')
+        assert len([x for x in content if 'is-loaded' in x]) == 2
+
+        # Test the mpileaks that should NOT have the autoloaded dependencies
+        content = modulefile_content('mpileaks ^mpich')
+        assert len([x for x in content if 'is-loaded' in x]) == 0