diff --git a/.buildkite/hooks/post-checkout b/.buildkite/hooks/post-checkout
index 8cdb3d7ad..a8871413c 100755
--- a/.buildkite/hooks/post-checkout
+++ b/.buildkite/hooks/post-checkout
@@ -5,7 +5,7 @@ set -euo pipefail
 # Buildkite users can trigger new builds with these values overridden to
 # test specific julia gitshas
 UPSTREAM_URL="${UPSTREAM_URL:-https://github.com/JuliaLang/julia.git}"
-UPSTREAM_BRANCH="${UPSTREAM_BRANCH:-master}"
+UPSTREAM_BRANCH="${UPSTREAM_BRANCH:-sf/core_o_rama}"
 
 # All of our workers are required to provide a default for the julia cache dir
 # We're going to cache repositories in here, just like buildkite itself would:
diff --git a/utilities/test_julia.sh b/utilities/test_julia.sh
index 07a99d5a0..5a49cb986 100755
--- a/utilities/test_julia.sh
+++ b/utilities/test_julia.sh
@@ -138,6 +138,9 @@ echo "JL_TERM_TIMEOUT is:        ${JL_TERM_TIMEOUT}"
 
 # Show our core dump file pattern and size limit if we're going to be recording them
 if [[ -z "${USE_RR-}" ]]; then
+    # Tell Julia to send `SIGQUIT` if something times out internally, generating a coredump
+    export JULIA_TEST_TIMEOUT_SIGNUM=3
+
     ulimit -c unlimited
     if [[ "${OS}" == linux* || "${OS}" == "musl" ]]; then
         echo "Core dump pattern:         $(cat /proc/sys/kernel/core_pattern)"
@@ -145,6 +148,7 @@ if [[ -z "${USE_RR-}" ]]; then
         echo "Core dump pattern:         $(sysctl -n kern.corefile)"
     fi
     echo "Core dump size limit:      $(ulimit -c)"
+    echo "Timeout signal set to:     ${JULIA_TEST_TIMEOUT_SIGNUM}"
 fi
 
 # Begin with "+++" => Expand test group by default