$ cat ~/.scons/site_scons/mongo_custom_variables.py
# We these for short_describe below.
import os
import subprocess

CCACHE="ccache"
ICECC="icecc"

# A little function that gives me a real mongo version, but without the git hash.
def short_describe():
    import os
    import subprocess
    with open(os.devnull, "r+") as devnull:
        proc = subprocess.Popen("git describe --abbrev=0",
            stdout=subprocess.PIPE,
            stderr=devnull,
            stdin=devnull,
            shell=True)
        return proc.communicate()[0].decode('utf-8').strip()[1:]

MONGO_VERSION=short_describe()
MONGO_GIT_HASH="unknown"

CC="/opt/mongodbtoolchain/v3/bin/clang"
CXX="/opt/mongodbtoolchain/v3/bin/clang++"

$ python3 buildscripts/scons.py --link-model=dynamic --ninja generate-ninja
$ ninja -j 500 build/install/bin/bson_test

$ build/install/bin/bson_test
...
{"t":{"$date":"2020-07-08T19:43:27.946Z"},"s":"I",  "c":"TEST",     "id":23068,   "ctx":"main","msg":"FAILURE","attr":{"failedTestsCount":4,"failedSuitesCount":2,"failedTests":["BSONElementIntegerParseTest/ParseIntegerElementToNonNegativeLongRejectsNonIntegralDecimal","BSONElementIntegerParseTest/ParseIntegerElementToLongRejectsNonIntegralDecimal","BSONElementIntegerParseTest/ParseIntegerElementToLongRejectsLargestDecimal","BSONObjCompare/NumberDecimalCompareDoubleNoDoubleRepresentation"]}}