support skip ci in azure pipelines, and support it properly in github actions pipelines (#17561)

* support skip ci in azure pipelines

* [skip ci] example of a commit that skips CI

* example of a commit that does not skip CI

* fix github actions logic for ci skip handling

* [skip ci] example of a commit that skips CI for all pipelines

* example of a commit that does not skip CI for any pipeline

.github/workflows/ci_docs.yml

@@ -30,8 +30,9 @@ on:
 
 jobs:
   build:
+    # see D20210329T004830
     if: |
-      !contains(format('{0} {1}', github.event.head_commit.message, github.event.pull_request.title), '[skip ci]')
+      !contains(format('{0}', github.event.pull_request.title), '[skip ci]')
     strategy:
       fail-fast: false
       matrix:
@@ -50,6 +51,16 @@ jobs:
     steps:
       - name: 'Checkout'
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 2
+
+      - name: 'Check whether to skip CI'
+        shell: bash
+        run: |
+          # see D20210329T004830
+          commitMsg=$(git log --no-merges -1 --pretty=format:"%s")
+          echo commitMsg: $commitMsg
+          echo $commitMsg | grep -v '\[skip ci\]'
 
       - name: 'Install build dependencies (macOS)'
         if: runner.os == 'macOS'

.github/workflows/ci_packages.yml

@@ -3,8 +3,9 @@ on: [push, pull_request]
 
 jobs:
   build:
+    # see D20210329T004830
     if: |
-      !contains(format('{0} {1}', github.event.head_commit.message, github.event.pull_request.title), '[skip ci]')
+      !contains(format('{0}', github.event.pull_request.title), '[skip ci]')
     strategy:
       fail-fast: false
       matrix:
@@ -19,6 +20,17 @@ jobs:
     steps:
       - name: 'Checkout'
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 2
+
+      - name: 'Check whether to skip CI'
+        shell: bash
+        run: |
+          # see D20210329T004830
+          commitMsg=$(git log --no-merges -1 --pretty=format:"%s")
+          echo commitMsg: $commitMsg
+          echo $commitMsg | grep -v '\[skip ci\]'
+
       - name: 'Checkout csources'
         uses: actions/checkout@v2
         with: