delete_values() fix bug #20681.

[lmello]

(#20681) fix behaviour of delete_values

The issue #20681 describe the error of delete() function
removing the elements from the origin array/hash/string.

This issue affected other delete functions. Because
ruby delete and delete_if functions make destructive
changes to the origin array/hash.

The delete_undef_values removed elements from the
origin hash and this is not the desired behaviour.

To solve this, we should dup or clone the hash
before using the delete or delete_if ruby functions.

This fix the problem and add unit tests, so we could
enforce this behaviour and prevent regressions.

[adrienthebo]

Thank you very much for this contribution! This looks great, but before we merge this I would like the commit message to match our project conventions. Once that's addressed we can merge this in.

Housekeeping - Commit Message

It would be good to have the commit message amended a little. The first line of the commit should have the issue number and a description of the problem or fix, and the body of the commit message should explain what is this existing behavior and how this change fixes it. We have a more complete explanation of this at https://github.com/puppetlabs/puppet/blob/master/CONTRIBUTING.md#making-changes .

[lmello]

Thanks for the explanation. i will change that tomorrow! :-)

[adrienthebo]

summary: merged into master in 1011670; thanks for the contribution!

[lmello]

Thanks !