Fix some pkg_resources variable types. (#3919)

Allow passing proper metadata to Distribution.from_location() and
Distribution.from_filename().

Correct the order of arguments for the importer functions.

Note that some functions accept any iterables, not just sized ones.

Correct the type of the VersionConflict classes' context.

third_party/3/pkg_resources/__init__.pyi

@@ -12,7 +12,7 @@ _InstallerType = Callable[[Requirement], Optional[Distribution]]
 _EPDistType = Union[Distribution, Requirement, str]
 _MetadataType = Optional[IResourceProvider]
 _PkgReqType = Union[str, Requirement]
-_DistFinderType = Callable[[str, _Importer, bool], Generator[Distribution, None, None]]
+_DistFinderType = Callable[[_Importer, str, bool], Generator[Distribution, None, None]]
 _NSHandlerType = Callable[[_Importer, str, str, types.ModuleType], str]
 
 def declare_namespace(name: str) -> None: ...
@@ -29,7 +29,7 @@ class WorkingSet:
     def __iter__(self) -> Generator[Distribution, None, None]: ...
     def find(self, req: Requirement) -> Optional[Distribution]: ...
     def resolve(
-        self, requirements: Sequence[Requirement], env: Optional[Environment] = ..., installer: Optional[_InstallerType] = ...
+        self, requirements: Iterable[Requirement], env: Optional[Environment] = ..., installer: Optional[_InstallerType] = ...
     ) -> List[Distribution]: ...
     def add(self, dist: Distribution, entry: Optional[str] = ..., insert: bool = ..., replace: bool = ...) -> None: ...
     def subscribe(self, callback: Callable[[Distribution], None]) -> None: ...
@@ -133,7 +133,7 @@ class Distribution(IResourceProvider, IMetadataProvider):
     def __init__(
         self,
         location: Optional[str] = ...,
-        metadata: Optional[str] = ...,
+        metadata: _MetadataType = ...,
         project_name: Optional[str] = ...,
         version: Optional[str] = ...,
         py_version: str = ...,
@@ -142,10 +142,10 @@ class Distribution(IResourceProvider, IMetadataProvider):
     ) -> None: ...
     @classmethod
     def from_location(
-        cls, location: str, basename: str, metadata: Optional[str] = ..., **kw: Union[str, None, int]
+        cls, location: str, basename: str, metadata: _MetadataType = ..., **kw: Union[str, None, int]
     ) -> Distribution: ...
     @classmethod
-    def from_filename(cls, filename: str, metadata: Optional[str] = ..., **kw: Union[str, None, int]) -> Distribution: ...
+    def from_filename(cls, filename: str, metadata: _MetadataType = ..., **kw: Union[str, None, int]) -> Distribution: ...
     def activate(self, path: Optional[List[str]] = ...) -> None: ...
     def as_requirement(self) -> Requirement: ...
     def requires(self, extras: Tuple[str, ...] = ...) -> List[Requirement]: ...
@@ -183,7 +183,7 @@ class IResourceManager:
     def resource_filename(self, package_or_requirement: _PkgReqType, resource_name: str) -> str: ...
     def set_extraction_path(self, path: str) -> None: ...
     def cleanup_resources(self, force: bool = ...) -> List[str]: ...
-    def get_cache_path(self, archive_name: str, names: Tuple[str, ...] = ...) -> str: ...
+    def get_cache_path(self, archive_name: str, names: Iterable[str] = ...) -> str: ...
     def extraction_error(self) -> None: ...
     def postprocess(self, tempname: str, filename: str) -> None: ...
 
@@ -209,11 +209,11 @@ class VersionConflict(ResolutionError):
     @property
     def req(self) -> Any: ...
     def report(self) -> str: ...
-    def with_context(self, required_by: Dict[str, Any]) -> VersionConflict: ...
+    def with_context(self, required_by: Set[Union[Distribution, str]]) -> VersionConflict: ...
 
 class ContextualVersionConflict(VersionConflict):
     @property
-    def required_by(self) -> Set[Any]: ...
+    def required_by(self) -> Set[Union[Distribution, str]]: ...
 
 class UnknownExtra(ResolutionError): ...