specify how we handle 200 OK and interpret 405 as no range requests

src/pip/_internal/network/lazy_wheel.py

@@ -279,6 +279,11 @@ def _try_initial_chunk_request(self, initial_chunk_size: int) -> tuple[int, byte
                 raise HTTPRangeRequestUnsupported(
                     "returned complete file contents instead of range"
                 )
+            # According to MDN at
+            # https://developer.mozilla.org/en-US/docs/Web/HTTP/Range_requests, a 200 OK
+            # implies that range requests are not supported, regardless of the
+            # requested size. We have decided to allow servers to respond with 200 OK if
+            # the file size was less than requested, even if this is nonstandard.
         elif code != codes.partial_content:
             raise HTTPRangeRequestUnsupported(
                 "did not receive partial content or ok: got code {code}"
@@ -303,7 +308,7 @@ def _extract_content_length(
             resp = e.response
             code = resp.status_code
             # Our initial request using a negative byte range was not supported.
-            if code == codes.not_implemented:
+            if code in [codes.not_implemented, codes.method_not_allowed]:
                 # pypi notably does not support negative byte ranges: see
                 # https://github.com/pypi/warehouse/issues/12823.
                 logger.debug(