disable parallel tox to avoid flaky failures

Disables parallel tox execution with
standard sequential execution.

Keeps comment pointing to pip bug that
made us disable parallel execution.

Removes bash code that was duplicating
functionality parallel execution support,
a feature which is part of tox, module named detox (shares same issue tracker as tox).

Change-Id: I835d0b87fa74bfe0a00a6ee0deb985912129e029
See: pypa/pip#5345

Author: ssbarnea

tox-gate.sh

@@ -1,36 +1,9 @@
 #!/bin/bash
 set -x
-RUN_ENVS="pep8 py27 cli ansible-lint any-errors-fatal conflicts plugin-registry"
+export TOXENV="pep8,py27,cli,ansible-lint,any-errors-fatal,conflicts,plugin-registry"
 
-FAILED=""
-run_tox() {
-    tox -e$1 &> .tox_$1_out &
-}
+# disabled parallel execution due to https://github.com/pypa/pip/issues/5345
+# which detox >/dev/null || pip install --user detox
+# python -m detox
 
-verify_tox() {
-    if ! tail -n2 .tox_$1_out | grep -q "$1: commands succeeded"; then
-        FAILED="${FAILED} $1"
-    else
-        echo -e "\033[01;33m_________ output of $1: _________\033[0m"
-        # failed outputs printed at the end
-        cat .tox_$1_out
-        echo -e "\033[01;33m====== ^^ end of $1 ^^ ======\033[0m"
-    fi
-}
-print_failed() {
-    for tEnv in ${FAILED}; do
-        echo -e "\033[01;33m_________ output of ${tEnv}: _________\033[0m"
-        cat .tox_${tEnv}_out;
-        echo -e "\033[01;31m====== ^^ end of failed ${tEnv} ^^ ======\033[0m"
-    done
-}
-
-for tEnv in ${RUN_ENVS}; do run_tox ${tEnv}; done
-wait
-set +x
-for tEnv in ${RUN_ENVS}; do verify_tox ${tEnv} || exit 1; done
-if [[ ! -z "$FAILED" ]]; then
-    print_failed
-    echo -e "\033[01;31m==== Failed: $FAILED ====\033[0m" >&2
-    exit 1
-fi
+python -m tox