No we can't actually uninstall selectors2, that breaks other tests.

.travis.yml

@@ -316,8 +316,6 @@ jobs:
     # PyPy is supported.
     - &test-dnspython-jobs
       script:
-        # https://github.com/gevent/gevent/issues/1641
-        - python -m pip uninstall -y selectors2
         - GEVENT_RESOLVER=dnspython python -mgevent.tests --coverage --ignore tests_that_dont_use_resolver.txt
       name: dnspython resolver (Python 2.7)
     # Now test the alternate backends, starting with libuv-cffi, which should be present everywhere

scripts/releases/make-manylinux

@@ -41,7 +41,11 @@ if [ -d /gevent -a -d /opt/python ]; then
 
     # Set a cache directory for pip. This was
     # mounted to be the same as it is outside docker so it
-    # can be persisted
+    # can be persisted.
+    # XXX: This works for macOS, where everything bind-mounted
+    # is seen as owned by root in the container. But when the host is Linux
+    # the actual UIDs come through to the container, triggering
+    # pip to disable the cache when it detects that the owner doesn't match.
     export XDG_CACHE_HOME="/cache"
     ls -ld /cache
     ls -ld /cache/pip