Merging / Bundling JS Files Production Mode breaks Regular Expressions

[ulftietze]

Preconditions

1. Magento 2.1.X (explict tested with 2.1.2, also shouldn't work with all other versions)
2. PHP 7.0.X
3. Production Mode
4. Enabled JS Bundling (Configuration > Advanced > Developer > JavaScript Settings)

Steps to reproduce

1. Create a custom JS File which should do some Regular Expressions (e.g. Input Fields in Checkout)
2. Inside if Validation e.g. do a /^([a-zA-ZßäöüÄÖÜ\s.]{3,})+$/
3. Run php bin/magento setup:static-content:deploy

Expected result

1. Regex should pass the following string: "Übergrößenträger"

Actual result

1. Can't validate this string, because REGEX Validation is modified to:
   /^([a-zA-Z\u00c3\u009f\u00c3\u00a4\u00c3\u00b6\u00c3\u00bc\u00c3\u0084\u00c3\u0096\u00c3\u009c\s.]{3,})+$/
2. This is after the json_encode of this string. Before Magento do this, here is the string that Magento creates: /^([a-zA-Z�äöü���\s.]{3,})+$/

[magento-team]

Internal ticket to track issue progress: MAGETWO-71647