going to POST as the backend fix is included in fine via ansible-client-ruby
Verified in 5.8.0.12-rc1.20170425180304_4f35996. It's possible to change credential name without filling in other fields again.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2017:1367