Regression in heredoc parser in 5.5.8

Puppet Version: 5.5.8
Puppet Server Version: N/A
OS Name/Version: N/A

Starting with Puppet 5.5.8, previously working code now fails to validate or compile:

$text = @("EOT")

         foo=${a}(value="${h['v']}")

         |EOT

Desired Behavior:
This code should validate and compile normally.

Actual Behavior:

# puppet parser validate test.pp

Error: Could not parse for environment production: Syntax error at '[' (file: /root/test.pp, line: 3, column: 12)

Note that the spacing, brackets, and parentheses must be of the form above to replicate the error. It seemed as though changing pretty much anything along those lines caused the error to disappear.

This looks to be a regression caused by the changes from https://github.com/puppetlabs/puppet/pull/7114/commits/49b42a55a181f7b68663edcd2e99fc21001f967b. If I back out that commit, the code validates and compiles as it did in Puppet 5.5.6.