To build pike from Git, you need to have a recent enough pike installed already. Apparently yours is too old:
precompile: pike /home/poppa/src/pike-git/devel/bin/precompile.pike --api=3 /home/poppa/src/pike-git/devel/src/builtin.cmod (method=QQQQQQ) /home/poppa/src/pike-git/devel/src/builtin.cmod:2091: Syntax error: string(8bit) is not a valid type.
test-pike is just one of the possible internally built pikes that are also tried in case they are more up-to-date.