Don't try to build the sources for src-8 after applying src-8.1725.gz without also applying src-8.1726.gz. I had to manually break this ctm update into two pieces. Note that src-8.1725.gz contains the fix to the "heartbleed" security breach announced in http://www.freebsd.org/security/advisories/FreeBSD-SA-14:06.openssl.asc.