This fix is a SCCOL variant of:

commit c66d1b9fcc2244b4fd8940f17ebf4e772f09c84e
Author: Kohei Yoshida <kyoshida@novell.com>
Date:   Thu May 5 00:23:25 2011 -0400

    fdo#36406: Let's not use invalidated iterators.

    std::set::erase(iterator) call invalidates the iterator of the erased
    element.  We better not use it after the erase() call.  Since the number
    of manual breaks should not be high enough to cause a performance
    bottleneck under normal usage, a safer linear copy should just be fine.

    Now, I'm not sure if this indeed is the cause of the erroneous amount
    of manual breaks in the test document, but I didn't see any other likely
    spot.

Change-Id: I0c2e8f738949776aa7f8ea5528e2c0eeb9351c16
Reviewed-on: https://gerrit.libreoffice.org/16063Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>