For the last few days (Since June 4?) I've been having problems with all my linux tests running against the develop branch. 

GCC ends with this:

gcc.compile.c++ ../../bin/common/build/gcc-8/release/process_jam_log.o

   "g++-8"   -fPIC -O3 -finline-functions -Wno-inline -Wall  -DBOOST_ALL_NO_LIB=1 -DNDEBUG -D_CRT_SECURE_NO_WARNINGS  -
I"/var/boost/run/boost_root" -c -o "../../bin/common/build/gcc-8/release/process_jam_log.o" "../../common/build/../src/p
rocess_jam_log.cpp"

../../common/build/../src/process_jam_log.cpp: In function 'std::__cxx11::string {anonymous}::revision(const string&)':
../../common/build/../src/process_jam_log.cpp:359:16: warning: ignoring return value of 'int system(const char*)', decla
red with attribute warn_unused_result [-Wunused-result]
    std::system("git rev-parse --short=6 HEAD >.short-sha");
    ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...skipped <p../../bin/testing/build/gcc-8/release>process_jam_log for lack of <p/var/boost/run/boost_root/bin.v2/libs/f
ilesystem/build/gcc-8/release/link-static/visibility-hidden>libboost_filesystem.a...