The choice of ':' as the field separator for table coprocessor specifications, which reside in HTableDescriptor attributes, was unfortunate because Hadoop FileSystem URIs will contain this character. So partly to simplify HBASE-4048 and partly for the sake of clarity, HBASE-4048 changes the field separator from ':' to '|'.
There are few if any people using table coprocessors at this time so the change is low impact now.
For those that are, simply updating the attribute in the HTD is all that is necessary.
Problems worthy of attack prove their worth by hitting back. - Piet Hein (via Tom White)