package.debian: Re-implement debian loader within the package loader mechanism

This introduces the debian package loader.

Contrary to other package loaders, a package can have multiple artifacts (per package version).

In those terms, we had to slightly adapt the swh.loader.package.loader.PackageLoader to demonstrate this. Thus the impacts on pypi, npm, deposit modules as well.

Related #2025 (closed) Related swh-core!91 (closed) Related swh-lister!114 (closed)

Test Plan

tox

---

Migrated from D2135 (view on Phabricator)

swh/loader/package/debian.py

@@ -74,9 +74,8 @@ def download_package(package: Dict, tmpdir: Any) -> Mapping[str, Dict]:
 
     """
     all_hashes = {}
-    for filename, fileinfo in copy.deepcopy(package['files']).items():
-        uri = fileinfo.pop('uri')
-        logger.debug('filename: %s', filename)
+    for filename, fileinfo in package['files'].items():
+        uri = fileinfo['uri']
         logger.debug('fileinfo: %s', fileinfo)
         extrinsic_hashes = {'sha256': fileinfo['sha256']}
         logger.debug('extrinsic_hashes(%s): %s', filename, extrinsic_hashes)
@@ -272,18 +271,18 @@ class DebianLoader(PackageLoader):
         return list(self.packages.keys())[0]
 
     def get_artifacts(self, version: str) -> Generator[
-            Tuple[str, str, Dict], None, None]:
-        url = ''  # url is not useful to retrieve the package files here
+            Tuple[Mapping[str, Any], Dict], None, None]:
         a_metadata = self.packages[version]
-        yield version, url, a_metadata  # we care only for version, a_metadata
+        artifacts_package_info = a_metadata.copy()
+        artifacts_package_info['filename'] = version
+        yield artifacts_package_info, a_metadata
 
     def resolve_revision_from(
             self, known_artifacts: Dict, artifact_metadata: Dict) \
             -> Optional[bytes]:
         pass  # for now
 
-    def download_package(self, a_uri: str, tmpdir: str, filename: str,
-                         a_metadata: Dict) -> Tuple[str, Dict]:
+    def download_package(self, a_p_info: str, tmpdir: str) -> Tuple[str, Dict]:
         """Contrary to other package loaders (1 package, 1 artifact),
         `a_metadata` represents the package's datafiles set to fetch:
         - <package-version>.orig.tar.gz
@@ -293,8 +292,8 @@ class DebianLoader(PackageLoader):
         This is delegated to the `download_package` function.
 
         """
-        logger.debug('debian: a_metadata: %s', a_metadata)
-        a_c_metadata = download_package(a_metadata, tmpdir)
+        logger.debug('debian: artifactS_package_info: %s', a_p_info)
+        a_c_metadata = download_package(a_p_info, tmpdir)
         return tmpdir, a_c_metadata
 
     def uncompress(self, a_path: str, tmpdir: str, a_metadata: Dict) -> str: