Fall back to commit hash in update tests

Travis CI occasionally has trouble figuring out the branch, so this
change makes sure it falls back to using at least a commit hash

scripts/docker-build.sh

@@ -12,7 +12,7 @@ BUILD_IMAGE_NAME=${BUILD_IMAGE_NAME:-$USER/pgbuild}
 IMAGE_NAME=${IMAGE_NAME:-$USER/timescaledb}
 GIT_BRANCH=$(git rev-parse --abbrev-ref HEAD ${BASE_DIR} | awk '{print $1; exit}' | sed -e "s|/|_|g")
 GIT_TAG=$(git -C ${BASE_DIR} rev-parse --short --verify HEAD)
-GIT_ID=$(git -C ${BASE_DIR} describe --dirty | sed -e "s|/|_|g")
+GIT_ID=$(git -C ${BASE_DIR} describe --dirty --always | sed -e "s|/|_|g")
 TAG_NAME=${TAG_NAME:-$GIT_ID}
 BUILD_TYPE=${BUILD_TYPE:-Debug}
 USE_OPENSSL=${USE_OPENSSL:-true}

scripts/test_update_from_tag.sh

@@ -12,7 +12,7 @@ CLEAN_PG_PORT=${CLEAN_PG_PORT:-6433}
 PG_VERSION=${PG_VERSION:-9.6.5} # Need 9.6.x version since we are
                                 # upgrading the extension from
                                 # versions that didn't support PG10.
-GIT_ID=$(git -C ${BASE_DIR} describe --dirty | sed -e "s|/|_|g")
+GIT_ID=$(git -C ${BASE_DIR} describe --dirty --always | sed -e "s|/|_|g")
 UPDATE_FROM_IMAGE=${UPDATE_FROM_IMAGE:-timescale/timescaledb}
 UPDATE_FROM_TAG=${UPDATE_FROM_TAG:-0.1.0}
 UPDATE_TO_IMAGE=${UPDATE_TO_IMAGE:-update_test}

scripts/test_updates.sh

@@ -7,7 +7,7 @@ TEST_TMPDIR=${TEST_TMPDIR:-$(mktemp -d 2>/dev/null || mktemp -d -t 'timescaledb_
 BASE_DIR=${PWD}/${SCRIPT_DIR}/..
 TAGS=${TAGS:-}
 TEST_VERSION=${TEST_VERSION:-}
-GIT_ID=$(git -C ${BASE_DIR} describe --dirty | sed -e "s|/|_|g")
+GIT_ID=$(git -C ${BASE_DIR} describe --dirty --always | sed -e "s|/|_|g")
 UPDATE_TO_IMAGE=${UPDATE_TO_IMAGE:-update_test}
 UPDATE_TO_TAG=${UPDATE_TO_TAG:-${GIT_ID}}
 PG_VERSION=${PG_VERSION:-9.6.5} # Need 9.6.x version since we are