BoundsError in MutableBinaryHeap delete! with 3 elements

[Firionus]

Similar to #611, but with three elements instead of two. This one wasn't fixed in #612.

Example

running julia --check-bounds=yes and then

julia> using DataStructures

julia> x = MutableBinaryMinHeap{Int}()
MutableBinaryHeap()

julia> h1 = push!(x,1)
1

julia> h2 = push!(x,2)
2

julia> h3 = push!(x,3)
3

julia> delete!(x, h3)
ERROR: BoundsError: attempt to access 2-element Array{DataStructures.MutableBinaryHeapNode{Int64},1} at index [3]
Stacktrace:
 [1] getindex at .\array.jl:809 [inlined]
 [2] _heap_bubble_down!(::Base.Order.ForwardOrdering, ::Array{DataStructures.MutableBinaryHeapNode{Int64},1}, ::Array{Int64,1}, ::Int64) at C:\Users\Johannes\.julia\packages\DataStructures\CINja\src\heaps\mutable_binary_heap.jl:46
 [3] _binary_heap_pop!(::Base.Order.ForwardOrdering, ::Array{DataStructures.MutableBinaryHeapNode{Int64},1}, ::Array{Int64,1}, ::Int64) at C:\Users\Johannes\.julia\packages\DataStructures\CINja\src\heaps\mutable_binary_heap.jl:124
 [4] delete!(::MutableBinaryHeap{Int64,Base.Order.ForwardOrdering}, ::Int64) at C:\Users\Johannes\.julia\packages\DataStructures\CINja\src\heaps\mutable_binary_heap.jl:273
 [5] top-level scope at REPL[17]:1

Im on [864edb3b] DataStructures v0.18.5. Same bug also appeared on [864edb3b] DataStructures v0.17.14, so it's not a regression.

Running the same code without --check-bounds=yes works as expected:

julia> using DataStructures

julia> x = MutableBinaryMinHeap{Int}()
MutableBinaryHeap()

julia> h1 = push!(x,1)
1

julia> h2 = push!(x,2)
2

julia> h3 = push!(x,3)#
3

julia> x
MutableBinaryHeap(1, 2, 3)

julia> delete!(x, h3)
MutableBinaryHeap(1, 2)

Note

Stumbled over it while writing a test, so tests seem to be run with bounds check. Why wouldn't this show up in the tests for DataStructures.jl?

Don't know how to fix it yet, haven't had time to look at the offending code.