Improve error message when egg-link does not match installed location

Include the locations of the mismatched locations in the message, to
provide more context.

src/pip/_internal/req/req_uninstall.py

@@ -532,8 +532,9 @@ def from_dist(cls, dist: Distribution) -> "UninstallPathSet":
                 link_pointer = os.path.normcase(fh.readline().strip())
             assert (
                 link_pointer == dist.location
-            ), "Egg-link {} does not match installed location of {} (at {})".format(
-                link_pointer, dist.project_name, dist.location
+            ), "Egg-link located at {} and pointing to {} does not match "\
+               "installed location of {} at {}".format(
+                develop_egg_link, link_pointer, dist.project_name, dist.location
             )
             paths_to_remove.add(develop_egg_link)
             easy_install_pth = os.path.join(