This update for enigmail fixes the following issues:

enigmail was updated to 2.1.5:

* Security issue: unsigned MIME parts displayed as signed (bsc#1159973)
* Ensure that upgrading GnuPG 2.0.x to 2.2.x upgrade converts keyring format
* Make Enigmail Compatible with Protected-Headers spec, draft 2

enigmail 2.1.4:

* Fixes for UI glitches
* Option to "Attach public key to messages" was not restored properly

enigmail 2.1.3:

* fix a bug in the setup wizard that could lead the wizard to
never complete scanning the inbox

This update was imported from the SUSE:SLE-15:Update update project.