pre-safe-import-hooks: create six.move runtime package only if six is…

… available

If the pre-safe-import hook for `six` (or one of its vendored
versions) cannot import `six` (or the corresponding vendored
version of it), do not create the `six.move` run-time
package in the modulegraph.

PyInstaller/hooks/pre_safe_import_module/hook-setuptools.extern.six.moves.py

@@ -26,13 +26,14 @@ def real_to_six_module_name():
             try:
                 import setuptools.extern.six as six
             except ImportError:
-                return {}  # unavailable
+                return None  # unavailable
 
         return {
             moved.mod: 'setuptools.extern.six.moves.' + moved.name
             for moved in six._moved_attributes if isinstance(moved, (six.MovedModule, six.MovedAttribute))
         }
 
-    api.add_runtime_package(api.module_name)
-    for real_module_name, six_module_name in real_to_six_module_name.items():
-        api.add_alias_module(real_module_name, six_module_name)
+    if real_to_six_module_name is not None:
+        api.add_runtime_package(api.module_name)
+        for real_module_name, six_module_name in real_to_six_module_name.items():
+            api.add_alias_module(real_module_name, six_module_name)

PyInstaller/hooks/pre_safe_import_module/hook-six.moves.py

@@ -36,7 +36,7 @@ def real_to_six_module_name():
         try:
             import six
         except ImportError:
-            return {}  # unavailable
+            return None  # unavailable
 
         # Iterate over the "six._moved_attributes" list rather than the "six._importer.known_modules" dictionary, as
         # "urllib"-specific moved modules are overwritten in the latter with unhelpful "LazyModule" objects. If this is
@@ -56,6 +56,7 @@ def real_to_six_module_name():
     # * Attributes imported from packages could be submodules. To disambiguate non-ignorable submodules from ignorable
     #   non-submodules (e.g., classes, variables), ModuleGraph first attempts to import these attributes as submodules.
     #   This is exactly what we want.
-    api.add_runtime_package(api.module_name)
-    for real_module_name, six_module_name in real_to_six_module_name.items():
-        api.add_alias_module(real_module_name, six_module_name)
+    if real_to_six_module_name is not None:
+        api.add_runtime_package(api.module_name)
+        for real_module_name, six_module_name in real_to_six_module_name.items():
+            api.add_alias_module(real_module_name, six_module_name)

PyInstaller/hooks/pre_safe_import_module/hook-urllib3.packages.six.moves.py

@@ -21,13 +21,14 @@ def real_to_six_module_name():
         try:
             import urllib3.packages.six as six
         except ImportError:
-            return {}  # unavailable
+            return None  # unavailable
 
         return {
             moved.mod: 'urllib3.packages.six.moves.' + moved.name
             for moved in six._moved_attributes if isinstance(moved, (six.MovedModule, six.MovedAttribute))
         }
 
-    api.add_runtime_package(api.module_name)
-    for real_module_name, six_module_name in real_to_six_module_name.items():
-        api.add_alias_module(real_module_name, six_module_name)
+    if real_to_six_module_name is not None:
+        api.add_runtime_package(api.module_name)
+        for real_module_name, six_module_name in real_to_six_module_name.items():
+            api.add_alias_module(real_module_name, six_module_name)