cmd/server: add a debug message saying which object caused a suggestion.
cmd/server: add a debug message saying which object caused a suggestion.

Let's use this to try to debug Aneurin's problem (and potentially others).

Signed-off-by: Avery Pennarun <e03ccfb89d416c4697ad6970ce86a92c1c28a78e@gmail.com>

apenwarr/bup,gevaerts/bup,pombredanne/bup,tjanez/bup,mhoeher/bup,gevaerts/bup,apenwarr/bup,ToxicFrog/bup,pombredanne/bup,tjanez/bup,mhoeher/bup,ToxicFrog/bup,ToxicFrog/bup,mhoeher/bup,jbaber/bup,jbaber/bup,tjanez/bup,ToxicFrog/bup,mhoeher/bup,jbaber/bup,pombredanne/bup,pombredanne/bup,gevaerts/bup,jbaber/bup,apenwarr/bup,ToxicFrog/bup,jbaber/bup,apenwarr/bup,gevaerts/bup,mhoeher/bup,mhoeher/bup,pombredanne/bup,tjanez/bup,pombredanne/bup,jbaber/bup,gevaerts/bup,tjanez/bup,tjanez/bup