Revert changes

Signed-off-by: Tushar Goel <tushar.goel.dav@gmail.com>

Author: TG1999

src/packageurl/__init__.py

@@ -178,7 +178,7 @@ def normalize_qualifiers(
     Raise ValueError on errors.
     """
     if not qualifiers:
-        return None
+        return None if encode else {}
 
     if isinstance(qualifiers, basestring):
         qualifiers_str = qualifiers if isinstance(qualifiers, str) else qualifiers.decode("utf-8")

src/packageurl/contrib/purl2url.py

@@ -78,8 +78,7 @@ def get_download_url(purl):
 
     # Fallback on the `download_url` qualifier when available.
     purl_data = PackageURL.from_string(purl)
-    if purl_data.qualifiers:
-        return purl_data.qualifiers.get("download_url", None)
+    return purl_data.qualifiers.get("download_url", None)
 
 
 def get_inferred_urls(purl):