readbytes!(s::IOStream, b::Array{Uint8}, nb=length(b)) does not respect nb argument

[lendle]

When reading from an IOStream, readbytes! reads length(b) bytes regardless of the nb.

Everything worked as expected when reading from an IOBuffer, so here is an example with a test file.

julia> f = open("testfile", "w")
       write(f, collect(0x01:0x0a))
       close(f);

julia> f = open("testfile")
       one = zeros(Uint8, 8)
       readbytes!(f, one, 3) #should be 3
8

julia> one #only first 3 bytes should be nonzero
8-element Array{Uint8,1}:
 0x01
 0x02
 0x03
 0x04
 0x05
 0x06
 0x07
 0x08


julia> seekstart(f); #reset f

julia> two = zeros(Uint8, 8)
       two[1:3] = readbytes(f, 3)
       two #this is what I expect "one" to be
8-element Array{Uint8,1}:
 0x01
 0x02
 0x03
 0x00
 0x00
 0x00
 0x00
 0x00