Pick off some low-hanging fruit from mypy checks

mypy.ini

@@ -28,7 +28,7 @@ ignore_errors = True
 [mypy-poetry.installation.*]
 ignore_errors = True
 
-[mypy-poetry.locations.*]
+[mypy-poetry.layouts.*]
 ignore_errors = True
 
 [mypy-poetry.mixology.*]
@@ -37,9 +37,6 @@ ignore_errors = True
 [mypy-poetry.packages.*]
 ignore_errors = True
 
-[mypy-poetry.plugins.*]
-ignore_errors = True
-
 [mypy-poetry.publishing.*]
 ignore_errors = True
 

poetry/locations.py

@@ -15,7 +15,8 @@ REPOSITORY_CACHE_DIR = Path(CACHE_DIR) / "cache" / "repositories"
 
 
 def data_dir() -> Path:
-    if os.getenv("POETRY_HOME"):
-        return Path(os.getenv("POETRY_HOME")).expanduser()
+    poetry_home = os.getenv("POETRY_HOME")
+    if poetry_home:
+        return Path(poetry_home).expanduser()
 
     return Path(user_data_dir("pypoetry", roaming=True))

poetry/plugins/plugin_manager.py

@@ -19,7 +19,7 @@ class PluginManager:
     def __init__(self, type, disable_plugins=False):  # type: (str, bool) -> None
         self._type = type
         self._disable_plugins = disable_plugins
-        self._plugins = []
+        self._plugins: List[Plugin] = []
 
     def load_plugins(self):  # type: () -> None
         if self._disable_plugins: