One of the generic repository Bamboo build variables are not getting substituted in plan Notifications url

Issue Summary

When we try to configure a notification based on commit id hash as the url end point , using "bamboo.planRepository.<position>.revision" variable the variable value is not getting substituted in the url.

This is reproducible on Data Center: yes

Steps to Reproduce

Try to intergate Bamboo with GITHUB.
Try sending Bamboo build status to GITHUB end point url.

It is not able to recognise the plan variable “bamboo.planRepository.revision” or “bamboo.planRepository.1.revision” and giving an error. When i give the complete url as below it works fine.

Works fine :- https://api.github.com/repos/anikredngold/testingcommit/statuses/dd61b5f6509dab2d109abaf2c5fd8f1b42151e41

Has issues :- https://api.github.com/repos/anikredngold/testingcommit/statuses/${bamboo.planRepository.revision}
https://api.github.com/repos/anikredngold/testingcommit/statuses/${bamboo.planRepository.1.revision}

Expected Results

Notification url will be able to substitute the "bamboo.planRepository.1.revision" variable with the commit hash i.e dd61b5f6509dab2d109abaf2c5fd8f1b42151e41

Actual Results

The below error is thrown in the webook tab of the plan

“Exception message
Illegal character in path at index 66: https://api.github.com/repos/anikredngold/testingcommit/statuses/${bamboo.planRepository.1.revision}”

Workaround

Use the complete url with the hash commit id