Description of problem:
trustdomain-find with pkey-only fails with message "an internal error has
occurred"

Version-Release number of selected component (if applicable):
ipa-server-3.3.3-17.el7.x86_64

How reproducible:
always

Steps to Reproduce:
1. Install IPA
2. Add trust with AD domain
3. Run
# ipa trustdomain-find --pkey-only ad.domain

Actual results:
[root@dhcp207-218 ~]# ipa trustdomain-find adtest.qe
  Domain name: adtest.qe
  Domain NetBIOS name: ADTEST
  Domain Security Identifier: S-1-5-21-1910160501-511572375-3625658879
  Domain enabled: True

  Domain name: pune.adtest.qe
  Domain NetBIOS name: PUNE
  Domain Security Identifier: S-1-5-21-91314187-2404433721-1858927112
  Domain enabled: True
----------------------------
Number of entries returned 2
----------------------------

[root@dhcp207-218 ~]# ipa trustdomain-find --pkey-only adtest.qe
ipa: ERROR: an internal error has occurred

[root@dhcp207-218 ~]# ipa trustdomain-find --pkey-only
Realm name: adtest.qe
ipa: ERROR: an internal error has occurred