at error: "modified someone else since you started" -> show the changes

[anonymous]

we are working with a lot of people at one track, sometimes many people with one ticket.

if you change the description or do a big comment, the error "modified someone else since you started" can make you crazy! :)

How about show at this page the commited description and comment, that the user can copy it to the clipboard and insert his changes again?

[cboos]

Duplicate of #4100, fixed for 0.11.