gen_server timeout has unhelpful error message

It's not clear if this error is something that's actionable by the user or not:

https://gist.github.com/wickedgrey/d2c87e6ee1e7c695abae

It sounds like there's a bug ("sloppy") here, but I'm not certain.

From IRC discussion:

4:40 PM rnewson: oh that's annoying
4:40 PM Wohali: gen_server timeout
4:40 PM rnewson: yeah, do we do a default timeout there for a view build? that's sloppy
4:40 PM Wohali: i bet, as it's not an os_process timeout
4:41 PM Wohali: which is what i would have expected to see
4:42 PM rnewson:
run(Pid, IdxState) ->
gen_server:call(Pid,

).

4:42 PM wickedgrey: the machine was in the middle of a test run at the time, which processes a lot of data under somewhat high load (roughly O(num_cores)), but we do this regularly and don't usually see this
4:42 PM rnewson:
couch_index_updater
ah, this one;
update(Mod, State) ->
update(nil, Mod, State).