Pipelines' YML file for Pull-Requests definitions

On the following documentation, it's defined that using the "pull-requests: '**'" definition will run Pipelines for every pull request created on the repository.

https://confluence.atlassian.com/bitbucket/configure-bitbucket-pipelines-yml-792298910.html#Configurebitbucket-pipelines.yml-ci_pull-requestspull-requests

However, if a pull request is created while having a source branch which does not include the "pull-requests: '**'" on the Bitbucket-pipelines.yml definition, the build is not triggered.

For example, lets suppose I have two branches, master and development, each with their YML set up like this:

In this case, it's not clear which YML file should be considered during the creation of the pull request. I would assume, in this case, that the YML to be considered here is the one on the destination branch, which contains the following definition for pull requests:

#!bash

pipelines:
  pull-requests:
    '**':

Creating the pull request, however, does not seem to trigger any builds: