gc error with .DS_Store

[hessammehr]

It seems like Pkg.gc() chokes on .DS_Store files sprinkled by macOS:

Pkg.gc()

ERROR: SystemError: unable to read directory /Users/hessammehr/.julia/packages/.DS_Store: Not a directoryStacktrace:
 [1] #walkdir#14(::Bool, ::Bool, ::typeof(throw), ::Function, ::String) at ./file.jl:0
 [2] walkdir at ./file.jl:700 [inlined]
 [3] (::getfield(Pkg.API, Symbol("#recursive_dir_size#48")))(::String) at /Users/osx/buildbot/slave/package_osx64/build/usr/share/julia/stdlib/v0.7/Pkg/src/API.jl:275
 [4] #gc#45(::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::Function, ::Pkg.Types.Context) at /Users/osx/buildbot/slave/package_osx64/build/usr/share/julia/stdlib/v0.7/Pkg/src/API.jl:314
 [5] gc at /Users/osx/buildbot/slave/package_osx64/build/usr/share/julia/stdlib/v0.7/Pkg/src/API.jl:273 [inlined] (repeats 2 times)
 [6] top-level scope at none:0