Remove FIXME from InstallRequirement.install (#7000)

This one is about whether we should error out when setup.py egg_info doesn't give us an .egg-info

src/pip/_internal/req/req_install.py

@@ -1000,7 +1000,6 @@ class InstallRequirement(object):
                         self,
                     )
                     # FIXME: put the record somewhere
-                    # FIXME: should this be an error?
                     return
             new_lines = []
             with open(record_filename) as f: