[MERGE][220067] add more specificity to the error message when split fails

[Jelmer Vernooij]

Jelmer Vernooij has voted tweak.
Status is now: Semi-approved
Comment:
The line of the error message is a bit long.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C4A2C73D3.9060806%40wartburg.edu%3E
Project: Bazaar