I've found that picosat-965 causes an assertion failure when picosat_push/picosat_pop are used with picosat_deref_partial. I came up with a small reproducible code. Please take a look at repro.c file.

Repro Steps:

./configure.sh --debug      # to include debugging code and symbols
make                        # build picosat-965
gcc repro.c ./libpicosat.a  # build repro.c
./a.out

Output:

Assertion failed: (best), function minautarky, file picosat.c, line 7082.
[1]    67622 abort      ./a.out

Tested Environments:

• Ubuntu-16.04 / x86_64 + gcc (Ubuntu 5.5.0-12ubuntu1~16.04)
• macOSX-10.14.1 + clang (Apple LLVM version 10.0.0 (clang-1000.11.45.5))