Revert "update-python-libraries: use version key for latest release (#68857)"

This broke support for --target.

This reverts commit e8c29fa77c.

pkgs/development/interpreters/python/update-python-libraries/update-python-libraries.py

@@ -116,11 +116,45 @@ SEMVER = {
 }
 
 
+def _determine_latest_version(current_version, target, versions):
+    """Determine latest version, given `target`.
+    """
+    current_version = Version(current_version)
+
+    def _parse_versions(versions):
+        for v in versions:
+            try:
+                yield Version(v)
+            except InvalidVersion:
+                pass
+
+    versions = _parse_versions(versions)
+
+    index = SEMVER[target]
+
+    ceiling = list(current_version[0:index])
+    if len(ceiling) == 0:
+        ceiling = None
+    else:
+        ceiling[-1]+=1
+        ceiling = Version(".".join(map(str, ceiling)))
+
+    # We do not want prereleases
+    versions = SpecifierSet(prereleases=PRERELEASES).filter(versions)
+
+    if ceiling is not None:
+        versions = SpecifierSet(f"<{ceiling}").filter(versions)
+
+    return (max(sorted(versions))).raw_version
+
+
 def _get_latest_version_pypi(package, extension, current_version, target):
     """Get latest version and hash from PyPI."""
     url = "{}/{}/json".format(INDEX, package)
     json = _fetch_page(url)
-    version = json['info']['version']
+
+    versions = json['releases'].keys()
+    version = _determine_latest_version(current_version, target, versions)
 
     try:
         releases = json['releases'][version]
@@ -132,7 +166,6 @@ def _get_latest_version_pypi(package, extension, current_version, target):
             sha256 = release['digests']['sha256']
             break
     else:
-        logging.error("Release not found for extension: {}".format(extension))
         sha256 = None
     return version, sha256