This is a corner case that doesn't happen in practice, but it can be created in
the test suite.

This holds a reference to the initial result, causing it to linger after
test_result_reset, thereby also holding a reference to the message context,
preventing it from being cleared. This in turn, can keep references to modified
message versions that cause the main message object to remain referenced. This
causes a panic in specific cases upon test_result_reset:

Panic: Input stream data unexpectedly has references

lib-sieve: multiscript: Fixed bug in handling of (implicit) keep; final keep action was executed as though there was a failure.
Among other things, this caused the keep action to revert back to the initial message, causing editheader actions to be ignored.

lib-sieve: editheader extension: Made protection against addition and deletion of headers configurable separately.
Also, the received and auto-submitted headers are now only protected against deletion as required in the RFC.
Updated the documentation accordingly.

NOTE: Dovecot doesn't currently MIME-encode these in the headers.

Forgot to rewind mail stream before header parsing.
Wrapped mail stream is obtained long before parsing, so if it is used in the mean time, it must be rewound to the beginning.

Forgot to increment count for the clone.

This was broken by previous change. It now properly uses the final version of the message
instead of the original.

It did not use the original message in this case.