[Bugzilla#18796] Try do.call(c, ans) instead of unlist() in tapply(simplify=TRUE)

[MichaelChirico]

https://bugs.r-project.org/show_bug.cgi?id=18796

Not sure all the subtle ways unlist(., recursive=FALSE, use.names=FALSE) might differ from do.call(c, .) besides method dispatch, but the method dispatch part at least WAI:

ans <- list(as.difftime(1, units='secs'), as.difftime(3, units='hours'))

unlist(ans)
# [1] 1 3

do.call(c, ans)
# Time differences in secs
# [1]     1 10800