aws-cdk: commit_message causes an incorrect environment variable

While using the cdk to create a codepipeline that has a github source action I would like to pass the environment variables down to subsequent steps.

self.source_variables = {
            "AUTHOR_DATE": codebuild.BuildEnvironmentVariable(value=self.source_action.variables.author_date),
            "BRANCH_NAME": codebuild.BuildEnvironmentVariable(value=self.source_action.variables.branch_name),
            "COMMIT_ID": codebuild.BuildEnvironmentVariable(value=self.source_action.variables.commit_id),
            # "COMMIT_MESSAGE": codebuild.BuildEnvironmentVariable(value=self.source_action.variables.commit_message),
            "COMMITTER_DATE": codebuild.BuildEnvironmentVariable(value=self.source_action.variables.committer_date),
            "COMMIT_URL": codebuild.BuildEnvironmentVariable(value=self.source_action.variables.commit_url),
            "REPOSITORY_NAME": codebuild.BuildEnvironmentVariable(value=self.source_action.variables.repository_name),
        }

However, if the line for commit_message is not commented out then I am met with an error that says the format is wrong: should be [{name, type, value}]

EnvironmentVariables specified in action config does not match expected format, the expected format is JSON array adhering to the following format: [{“name”: “string”, “type”: “string”, “value”: “string”}]

the issue is not present with any other value.

Reproduction Steps

Create a simple codepipeline with a GithubSourceAction and a codebuild action like:

self.build_init_action = actions.CodeBuildAction(
            action_name="initialize",
            project=build_project,
            input=self.source,
            outputs=[],
            environment_variables=self.source_variables
        )

The deploy command will succeed but the details for the second stage will not work with the commit_message.

Error Log

No Errors except when in the console.

EnvironmentVariables specified in action config does not match expected format, the expected format is JSON array adhering to the following format: [{“name”: “string”, “type”: “string”, “value”: “string”}]

Environment

• CLI Version : 1.45
• Framework Version: 1.45
• Node.js Version: v14.3.0
• OS : manjaro linux and mac osx
• Language (Version): python 3.8.3

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This is 🐛 Bug Report

It is equally as likely that I am just missing something wildly dumb.

I can provide cf templates at request.