This is the error.
Do you store Slicer source code in a git repository, or it is just a plain local folder?
If it is a plain local folder then you need to specify the working copy information (the build system needs that to make some decisions), but the proper solution is to use a revision-controlled folder for the source code.
If you store Slicer in a git repository then the data extraction may fail due to regional settings in your computer (how dates are formatted). See more details (what additional information we would need for the investigation) here.