Any projects which want to use Hush code from now on will need to be licensed as
GPLv3 or we will send the lawyers: https://www.softwarefreedom.org/
Notably, Komodo (KMD) is licensed as GPLv2 and is no longer compatible to receive
code changes, without causing legal issues. MIT projects, such as Zcash, also cannot pull
in changes from the Hush Full Node without permission from The Hush Developers,
which may in some circumstances grant an MIT license on a case-by-case basis.
This fixes a subtle bug involving block re-orgs and non-standard transactions.
Start with a block containing a non-standard transaction, and
one or more transactions spending it in the memory pool.
Then re-org away from that block to another chain that does
not contain the non-standard transaction.
Result before this fix: the dependent transactions get stuck
in the mempool without their parent, putting the mempool
in an inconsistent state.
Tested with a new unit test.