Xearth does not update...

... because every new version will have a version code lower than 2015100901.

See Error log: https://f-droid.org/wiki/page/de.drhoffmannsoftware.xearth and https://f-droid.org/packages/de.drhoffmannsoftware.xearth/

So any new version build had been disabled (manually(?) for unknown reason). But I think this is an error, because instead the version with version code 2015100901 should have been disabled, so that the current and future versions build correctly.