bug#23470: Feature request: preserve breakpoints when C-u C-M-x function definitions

[Paul Pogonyshev]

When I re-evaluate (C-M-x) a function definition that has breakpoints,
all of them are lost. This is particularly annoying when breakpoints
are conditional, because now I not only have to recreate them
manually, but also specify all the conditions again.

Request: preserve existing breakpoints within definitions where
possible. One idea suggested on the devel list is to assign a marker
to each breakpoint and recreate it at the new marker position when
re-evaluating, as long as marker is not deleted (related to
bug#23468).