catch an exception when parsing metadata which only occurs in CI

src/pip/_internal/operations/prepare.py

@@ -4,6 +4,7 @@
 # The following comment should be removed at some point in the future.
 # mypy: strict-optional=False
 
+import email.errors
 import json
 import mimetypes
 import os
@@ -455,11 +456,19 @@ def _cache_metadata(
     ) -> None:
         if self._metadata_cache is None:
             return
-        with self._metadata_cache.cache_path(link).open("w") as f:
-            cacheable_dist = CacheableDist.from_dist(link, metadata_dist)
-            args = cacheable_dist.to_json()
-            logger.debug("caching metadata for link %s at %s", link.url, f.name)
-            json.dump(args, f)
+        try:
+            with self._metadata_cache.cache_path(link).open("w") as f:
+                cacheable_dist = CacheableDist.from_dist(link, metadata_dist)
+                args = cacheable_dist.to_json()
+                logger.debug("caching metadata for link %s at %s", link.url, f.name)
+                json.dump(args, f)
+        except email.errors.HeaderParseError as e:
+            logger.debug(
+                "could not cache metadata for dist %s from %s: %s",
+                metadata_dist,
+                link,
+                e,
+            )
 
     def _fetch_metadata_using_link_data_attr(
         self,