The default portsnap server is corrupt. "portsnap fetch" shows ~4xMB, then extract terminates with a truncated gz, while "portsnap -s portsnap2 fetch" shows ~6xMB and completes the extract.
Colin is probably the right guy to look at this.
Peter is looking after addressing service impacts due to an attack on ISC where some of our services are hosted, which may be related and was announced on developers@ yesterday
While the size of the portsnap now matches, I have been getting pkg-static: invalid chunk added pkg: invalid chunk added when trying to build or use /usr/ports/pkg-mgmt/pkg on a fresh 10.0 system. Dumping /usr/ports & doing a new extract from portsnap2 has the same result. I don't know if this is something to report to the port maintainer, or is related to the mirror problem. Systems built on the 8th don't have that problem.
This should be fixed per cperciva Please file another PR if this recurs.