test-libmongoc aborts or (rarely) segfaults when a test fails. Printing a backtrace would be nice, especially in Evergreen.

On Linux and perhaps Mac, these instructions provide a starting place:

http://stackoverflow.com/questions/77005/how-to-generate-a-stacktrace-when-my-gcc-c-app-crashes

http://www.gnu.org/software/libc/manual/html_node/Backtraces.html

http://oroboro.com/stack-trace-on-crash/

On Windows apparently it's harder, leave that for later and see how the server implements backtraces.