A marked as trusted certificate cannot be written in a softhsmv2 db

I used softhsm-2.0.0b1 from fedora 21 and trying to write a certificate in a softhsm db with CKA_TRUSTED fails with:
P11Attributes.cpp(407): A trusted certificate cannot be modified

How reproducible:
1. cat >config
directories.tokendir = db
objectstore.backend = file

2. export SOFTHSM2_CONF=config
3. mkdir db
4. softhsm2-util --init-token --slot 0 --label test --so-pin 1234 --pin 1234
5. p11tool --provider /usr/lib64/pkcs11/libsofthsm2.so --write --mark-trusted --load-certificate any-cert.pem --label test --so-login

Output:
Error writing certificate: PKCS #11 error in attribute

Expected Output:
Success.

Writing the same certificate without the mark-trusted flag works fine.

This seems to be a regression from version 1, as this use case works properly with softhsmv1. The p11tool is from gnutls utils.

I attach the output from pkcs11-spy for the failed operation.