phabricator-refresh: add a magic value to skip it in the CI

When maintaining (light) fork, it is useful to be able to disable this.

Differential Revision: https://phab.mercurial-scm.org/D12133

contrib/heptapod-ci.yml

@@ -56,6 +56,11 b' rust-cargo-test-py3:'
 
 phabricator-refresh:
     stage: phabricator
+    rules:
+      - if: '"$PHABRICATOR_TOKEN" != "NO-PHAB"'
+        when: on_success
+      - if: '"$PHABRICATOR_TOKEN" == "NO-PHAB"'
+        when: never
     variables:
       DEFAULT_COMMENT: ":white_check_mark: refresh by Heptapod after a successful CI run (:octopus: :green_heart:)"
       STABLE_COMMENT: ":white_check_mark: refresh by Heptapod after a successful CI run (:octopus: :green_heart:)\n⚠ This patch is intended for stable ⚠\n{image https://media.giphy.com/media/nYI8SmmChYXK0/source.gif}"

contrib/phab-refresh-stack.sh

@@ -1,6 +1,11 b''
 #!/bin/bash
 set -eu
 
+if [[ "$PHABRICATOR_TOKEN" == "NO-PHAB" ]]; then
+    echo 'Skipping Phabricator Step' >&2
+    exit 0
+fi
+
 revision_in_stack=`hg log \
     --rev '.#stack and ::. and topic()' \
     -T '\nONE-REV\n' \
@@ -27,6 +32,7 b' fi'
 
 if [[ "$PHABRICATOR_TOKEN" == "" ]]; then
     echo 'missing $PHABRICATOR_TOKEN variable' >&2
+    echo '(use PHABRICATOR_TOKEN="NO-PHAB" to disable this step)' >&2
     exit 2
 fi