Fix tests by explicitly passing TEST_TMPDIR to mk*temp.

We need to tell mktemp to explicitly create temporary files and
directories under TEST_TMPDIR.  The default of picking up the TMPDIR
value (which may be unset) or /tmp may not work and was causing two
tests to fail.  I suspect that paths outside of TEST_TMPDIR may not
be writable due to our sandboxing features.

--
MOS_MIGRATED_REVID=131957733

scripts/bash_completion_test.sh

diff --git a/scripts/bash_completion_test.sh b/scripts/bash_completion_test.sh
index 82a0fa3..1f261bc 100755
--- a/scripts/bash_completion_test.sh
+++ b/scripts/bash_completion_test.sh
@@ -99,7 +99,7 @@
 # in STDERR receiving a string containing regex unexpected-error.
 assert_expansion_error_not_contains() {
   local prefix=$1 not_expected=$2 flags=${3:-}
-  local temp_file=$(mktemp -t tmp.stderr.XXXXXX)
+  local temp_file="$(mktemp "${TEST_TMPDIR}/tmp.stderr.XXXXXX")"
   for i in ${COMMAND_ALIASES[@]}; do
     local nprefix="$i "
     expand "$nprefix\t" "$flags" "$temp_file" > /dev/null

src/test/shell/bazel/bazel_rules_test.sh

diff --git a/src/test/shell/bazel/bazel_rules_test.sh b/src/test/shell/bazel/bazel_rules_test.sh
index cd51087..b34a26b 100755
--- a/src/test/shell/bazel/bazel_rules_test.sh
+++ b/src/test/shell/bazel/bazel_rules_test.sh
@@ -231,8 +231,7 @@
 EOF
   local old_path="${PATH}"
   local old_tmpdir="${TMPDIR-}"
-  local effective_tmpdir="${TMPDIR:-/tmp}"
-  local new_tmpdir=$(mktemp -d "${effective_tmpdir}/newfancytmpdirXXXXXX")
+  local new_tmpdir="$(mktemp -d "${TEST_TMPDIR}/newfancytmpdirXXXXXX")"
   [ -d "${new_tmpdir}" ] || \
     fail "Could not create new temporary directory ${new_tmpdir}"
   export PATH="/bin:/usr/bin:/random/path"