diff --git a/.build/docker/_build-debian.sh b/.build/docker/_build-debian.sh
index 7d92d6eb07..c25d168b85 100755
--- a/.build/docker/_build-debian.sh
+++ b/.build/docker/_build-debian.sh
@@ -21,6 +21,8 @@
 #
 ################################
 
+[ $DEBUG ] && set -x
+
 # variables, with defaults
 [ "x${CASSANDRA_DIR}" != "x" ] || CASSANDRA_DIR="$(readlink -f $(dirname "$0")/..)"
 [ "x${DIST_DIR}" != "x" ] || DIST_DIR="${CASSANDRA_DIR}/build"
@@ -96,7 +98,7 @@ else
     # if CASSANDRA_VERSION is -alphaN, -betaN, -rcN, it fails on the '-' char; replace with '~'
     CASSANDRA_VERSION=${buildxml_version/-/\~}
     dt=`date +"%Y%m%d"`
-    ref=`git rev-parse --short HEAD || grep -q GitSHA src/resources/org/apache/cassandra/config/version.properties && grep GitSHA src/resources/org/apache/cassandra/config/version.properties | cut -d"=" -f2 || echo unknown`
+    ref=`git rev-parse --short HEAD || ( grep -q GitSHA src/resources/org/apache/cassandra/config/version.properties && grep GitSHA src/resources/org/apache/cassandra/config/version.properties | cut -d"=" -f2 ) || echo unknown`
     CASSANDRA_REVISION="${dt}git${ref}"
     dch -D unstable -v "${CASSANDRA_VERSION}-${CASSANDRA_REVISION}" --package "cassandra" "building ${CASSANDRA_VERSION}-${CASSANDRA_REVISION}"
 fi
@@ -128,4 +130,4 @@ rm -f cassandra-build-deps_*
 # restore debian/changelog
 git restore debian/changelog || true
 
-popd >/dev/null
\ No newline at end of file
+popd >/dev/null
diff --git a/.build/docker/_docker_run.sh b/.build/docker/_docker_run.sh
index 6aafc74157..4a2aa16c5b 100755
--- a/.build/docker/_docker_run.sh
+++ b/.build/docker/_docker_run.sh
@@ -116,6 +116,8 @@ random_string="$(LC_ALL=C tr -dc A-Za-z0-9 </dev/urandom | head -c 6 ; echo '')"
 run_script_name=$(echo ${run_script} | sed  's/.sh//' | sed 's/_//')
 container_name="cassandra_${dockerfile/.docker/}_${un_script_name}_jdk${java_version}__${random_string}"
 
+[ $DEBUG ] && docker_envs="${docker_envs} --env DEBUG=1"
+
 # Docker commands:
 #  change ant's build directory to $DIST_DIR
 #  set java to java_version
@@ -128,7 +130,7 @@ docker_command="export ANT_OPTS=\"-Dbuild.dir=\${DIST_DIR} ${CASSANDRA_DOCKER_AN
 # re-use the host's maven repository
 container_id=$(docker run --name ${container_name} -d --security-opt seccomp=unconfined --rm \
     -v "${cassandra_dir}":/home/build/cassandra -v ${m2_dir}:/home/build/.m2/repository/ -v "${build_dir}":/dist \
-    ${docker_volume_opt} \
+    ${docker_envs} ${docker_volume_opt} \
     ${image_name} sleep 1h)
 
 echo "Running container ${container_name} ${container_id} using image ${image_name}"
diff --git a/.build/docker/build-debian.sh b/.build/docker/build-debian.sh
index ae2058013c..e265fa5e8d 100755
--- a/.build/docker/build-debian.sh
+++ b/.build/docker/build-debian.sh
@@ -15,6 +15,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+[ $DEBUG ] && set -x
 
 if [ "$1" == "-h" ]; then
    echo "$0 [-h] [<java_version>]"
diff --git a/CHANGES.txt b/CHANGES.txt
index a1129aafd5..e797466f13 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -7,6 +7,7 @@
 Merged from 4.1:
  * Fix race condition in DecayingEstimatedHistogramReservoir during rescale (CASSANDRA-19365)
 Merged from 4.0:
+ * Fix bash-completion for debian distro (CASSANDRA-19999)
  * Ensure thread-safety for CommitLogArchiver in CommitLog (CASSANDRA-19960)
  * Fix text containing "/*" being interpreted as multiline comment in cqlsh (CASSANDRA-17667)
  * Fix indexing of a frozen collection that is the clustering key and reversed (CASSANDRA-19889)
diff --git a/debian/nodetool-completion b/debian/nodetool-completion
index c17af0f525..b62a178193 100644
--- a/debian/nodetool-completion
+++ b/debian/nodetool-completion
@@ -15,7 +15,7 @@
 # limitations under the License.
 #
 #
-have nodetool && have cqlsh &&
+_have nodetool && _have cqlsh &&
 {
 
     show_keyspaces()