String Corruption in Ruby 2.6.4

Hello,

When we upgraded one of our applications, we started seeing string corruption. That is, a strings' content would change seemingly randomly and contain nonsense characters, like null characters (\x00). However, the changes to the string are not deterministic. The errors we see are something like:

ActionView::Template::Error: undefined method `"plaintiff_profile_extension_id\x00eq"'

This issue was also reported here: https://bugs.ruby-lang.org/issues/16136

Unfortunately it looks like registration on the bug tracker is not working, so I cannot create an account to add details to the existing bug. We did however use "git bisect" to determine that the git commit that introduced the behavior is:

da36d5700d9e0e66411d93595b6f654c85853fa1 is the first bad commit
commit da36d5700d9e0e66411d93595b6f654c85853fa1
Author: nagachika <nagachika@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>

    merge revision(s) 53e9908d8afc7f03109b0aafd1698ab35f512b05: [Backport #15916]

Thank you,
-- Kevin Jones

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Date: Wed Aug 7 12:03:52 2019 +0000