Offset arrays indexing of indexes bug

[andyferris]

I found some questionable behavior regarding indices of OffsetArrays.

julia> include("test/TestHelpers.jl")
Main.TestHelpers

julia> using Main.TestHelpers.OAs

julia> a = [11,12,13]
3-element Array{Int64,1}:
 11
 12
 13

julia> b = OffsetArray(a, (-3,))
OffsetArray{Int64,1,Array{Int64,1}} with indices -2:0:
 11
 12
 13

julia> i = LinearIndices(b)
LinearIndices{1,Tuple{Base.Slice{UnitRange{Int64}}}} with indices -2:0:
 -2
 -1
  0

julia> i[-2]
-2

julia> i[-2:end]
-5:-3

I suspect this is a bug. Because these are a Slice I feel the scalar getindex behavior is correct and the behavior here is wrongly assuming 1-based indexing.