Fix AppVeyor doc short-circuit (GH-5634)

(cherry picked from commit 6ea20fc719dcaf102d2cefa1786f0421514f7a58)

diff --git a/.github/appveyor.yml b/.github/appveyor.yml
index 6e6a078a10326772422ec15b191b999e38a58ef9..e26969664ec29c56593fc0e0c3abc92fb2c0e2b7 100644 (file)
--- a/.github/appveyor.yml
+++ b/.github/appveyor.yml
@@ -14,12 +14,15 @@ before_build:
       } elseif (!$env:APPVEYOR_PULL_REQUEST_HEAD_COMMIT) {
         echo 'Not a PR, doing full build.'
       } else {
-        $mergebase = git merge-base $env:APPVEYOR_PULL_REQUEST_HEAD_COMMIT $env:APPVEYOR_REPO_BRANCH
+        git fetch -q origin +refs/heads/$env:APPVEYOR_REPO_BRANCH
+        $mergebase = git merge-base HEAD FETCH_HEAD
         $changes = git diff --name-only HEAD $mergebase | grep -vE '(\.rst$)|(^Doc)|(^Misc)'
         If (!$changes) {
           echo 'Only docs were updated, stopping build process.'
           Exit-AppveyorBuild
         }
+        echo 'Doing full build due to non-doc changes in these files:'
+        echo $changes
       }