Azure Devops Running Two Builds Sequentially

Question

We have Azure Devops setup. Right now our Project will Build Twice.

Once during Pull Request Checkin in the YAML file, and another due to Build Settings (picture below).<

Answer 1

Functionally the two build may not always be the same.

Lets say you have the below example. Capital letters are commits and lower-case letters are potential commits.

  e e'
 /   \
|  |   D
C  |   B 
 \ |  /
   A

This shows, two branches coming off of the A commit (master branch). Each feature branch had a PR created for each one. One branch has a build on the e commit and the other branch had a build on the e' commit. Azure devops cannot be sure which PR will be merged first.

Once you merge both of the PR's you will end up with a new commit in master that has not been previously built. This is described here

   F
   E \
 / |   D
C  |   B 
 \ |  /
   A

If you want to eliminate the need for your build on master, you can set the build expiration to Immediately when branch name is updated