As we found out with I88751ed6df7d5f9dad735171e19f82dea745b4da and the
resulting downtime, cgit does not like multi-line description values.
The cgit(5) man page is conspicuously quiet on quoting or multi-line
values; let's just ensure we don't do this again. This does detect
the newlines in the original change.
Change-Id: I87bcff409d4632c70bff5e4606b4572c38c74e59