Pytest 4 compatibility

Resolves https://bugzilla.redhat.com/show_bug.cgi?id=1694177

python-pip.spec

@@ -101,6 +101,9 @@ Patch3:         remove-existing-dist-only-if-path-conflicts.patch
 # https://bugzilla.redhat.com/show_bug.cgi?id=1655253
 Patch4:         dummy-certifi.patch
 
+# pytest 4 support
+Patch5:         https://github.com/pypa/pip/commit/d4264dc3b2ab292c9843fb1d001c7fc0a5fc67c4.patch
+
 # Downstream only patch
 # Users might have local installations of pip from using
 # `pip install --user --upgrade pip` on older versions.
@@ -272,6 +275,7 @@ popd
 %patch2 -p1
 %patch3 -p1
 %patch4 -p1
+%patch5 -p1
 
 # this goes together with patch4
 rm src/pip/_vendor/certifi/*.pem