I have an iron pick that has only one enchantment (unbreaking III) it was renamed back while we still played 1.7.4 version. I had no problems repairing it since we started playing with the snapshots, until yesterday when I wanted to repair it, as soon as it was put on the anvil it said "too expensive" which from my understanding shouldn't be the case with a renamed tool.
Duplicate of MC-45300 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.