gzip compress link metadata for a slight reduction in disk space

src/pip/_internal/operations/prepare.py

@@ -5,6 +5,7 @@
 # mypy: strict-optional=False
 
 import email.errors
+import gzip
 import json
 import mimetypes
 import os
@@ -437,7 +438,7 @@ def _fetch_cached_metadata(
         try:
             cached_path = self._metadata_cache.cache_path(req.link)
             os.makedirs(str(cached_path.parent), exist_ok=True)
-            with cached_path.open("rb") as f:
+            with gzip.open(cached_path, mode="rt", encoding="utf-8") as f:
                 logger.debug(
                     "found cached metadata for link %s at %s", req.link, f.name
                 )
@@ -466,7 +467,7 @@ def _cache_metadata(
         try:
             cached_path = self._metadata_cache.cache_path(req.link)
             os.makedirs(str(cached_path.parent), exist_ok=True)
-            with cached_path.open("w") as f:
+            with gzip.open(cached_path, mode="wt", encoding="utf-8") as f:
                 cacheable_dist = CacheableDist.from_dist(req.link, metadata_dist)
                 args = cacheable_dist.to_json()
                 logger.debug("caching metadata for link %s at %s", req.link, f.name)