Unable to create a pipeline using the UI when repository requires issue key

Issue Summary

Currently, when the repository has integration with an issue tracker and the Require issue keys in commit messages option is enabled, it´s not possible to create a pipeline using the Bitbucket UI's Pipeline section.

Steps to Reproduce

1. Link a Bitbucket repository, that has no pipeline configured, to an issue tracker (Jira in this example) **
2. Under Repository Settings > Workflows > Links, enable the option Require issue keys in commit messages
3. Go to the repository's Pipeline section and create a new pipeline using any of the templates
4. Try to commit the pipeline YAML file, and it will fail with the message: "Committing file was unsuccessful. You may have restricted write access to the branch."**

This happened because the default commit message of the YAML file created when you first commit your pipeline through the UI is "Initial Bitbucket Pipelines configuration". This message cannot be changed, and since it has no Issue Key, Bitbucket is not allowing the commit, and showing a generic access issue message.

Expected Results

The correct error message is shown, stating the commit failed because of a missing issue key, and allow commit message to be edited.

Actual Results

The default commit message cannot be changed and a generic error message about branch write permissions was showed.

Workaround

Manually create the bitbucket-pipelines.yml file and push it to the repository with a commit message containing an issue Key.