=> Bootstrap dependency digest>=20010302: found digest-20190127
=> Fetching mono-4.0.4.1.tar.bz2
=> Total size: 96106273 bytes
ftp: Error retrieving file `503 Backend unavailable, connection failed'
fetch: Unable to fetch expected file mono-4.0.4.1.tar.bz2
=> Checksum SHA1 OK for mono-4.0.4.1.tar.bz2
=> Checksum RMD160 OK for mono-4.0.4.1.tar.bz2
=> Checksum SHA512 OK for mono-4.0.4.1.tar.bz2