SHA-1.
On a related note, I have problems building 7.4. I get
configure: configuring in _Regexp_PCRE configure: running /bin/bash /home/nilsson/Pike/7.4/src/modules/../configure --prefix=/usr/local '--prefix=/usr/local' '--cache-file=.././config.cache' '--srcdir=/home/nilsson/Pike/7.4/src/modules' --cache-file=../.././config.cache --srcdir=/home/nilsson/Pike/7.4/src/modules/_Regexp_PCRE configure: error: cannot find sources (interpret.c) in /home/nilsson/Pike/7.4/src/modules/_Regexp_PCRE configure: error: /bin/bash /home/nilsson/Pike/7.4/src/modules/../configure failed for _Regexp_PCRE configure: error: /home/nilsson/Pike/7.4/src/modules/configure failed for modules make: *** [config.status] Error 1
which confuses me, as configure.in doesn't mention interpret.c at all.