From: Yusei Tahara

    I think it was a network problem. If you try again, it should work.

 

I think it's related to https://github.com/Nexedi/erp5/commit/
b5b16628d0753647b87b4b7ff6c72eb32c3b224f#diff-8903239df476d7401cf9e76af0252622 
.

You remove submodule "doc-bt5", but installer don't know about it.