In the new version CutPruners v0.1.0, DocStringExtensions is not part of the REQUIRE file of CutPruners anymore.
However, this package uses DocStringExtensions in its latest release (v0.5.0) but it is not present in it REQUIRE file hence relying on the fact that CutPruners has it to work on Travis.
This makes CI fail on METADATA because this packages fails with the new release of CutPruners.
In the new version CutPruners v0.1.0, DocStringExtensions is not part of the REQUIRE file of CutPruners anymore. However, this package uses DocStringExtensions in its latest release (v0.5.0) but it is not present in it REQUIRE file hence relying on the fact that CutPruners has it to work on Travis. This makes CI fail on METADATA because this packages fails with the new release of CutPruners.