PR build not getting triggered on update

This is the configuration I am using

```
 org.jenkinsci.plugins.ghprb.GhprbTrigger.xml: |-


1
.*add\W+to\W+whitelist.*
.*ok\W+to\W+test.*
.*test\W+this\W+please.*
.*\[skip\W+ci\].*

H/5 * * * *
false
false
true
FAILURE
false
false



false
false



false



```

So when i raise a PR on repo, PR-number #1 build get trigger. If I update the PR or basically push a commit to PR while the first build is ongoing then #2 is not getting triggered. If I update the PR after #1 is complete then #2 is getting triggered. Is this related to this plugin or something else. Can someone please help me? Thanks in advance

Start with the GhprbTrigger.xml configuration shown in the issue, especially the GhprbCancelBuildsOnUpdate extension, and reproduce an update while the first pull-request build is running. Trace the plugin's update and build-cancellation behavior; done means a new build is triggered for a pull-request update without waiting for the previous build to finish.

Written by the indexing model from the issue text.