broadcasting and map are not type inferrable

The following code does not infer properly:
```julia
using DistributedArrays
addprocs(1)
a = distribute(rand(10), procs = [1,2])
f(x) = log.(x)
@code_warntype f(a)
@code_warntype map(log, a)
```

Start by running the Julia reproduction with DistributedArrays, addprocs, distribute, broadcasting, map, and @code_warntype. Trace the DistributedArrays paths used by f(a) and map(log, a); the issue is done when both expressions infer appropriately, but no files or tests are identified in the report.

Scritto dal modello di indicizzazione a partire dal testo della issue.