JuliaのPkg.addでIJuliaがインストールできない

Windows10でJuliaのREPLから下記のように実行するとこのようなエラーがでてきてしまいます。原因が分かる方いらっしゃいますか？

julia
1   _       _ _(_)_     |  A fresh approach to technical computing
2  (_)     | (_) (_)    |  Documentation: https://docs.julialang.org
3   _ _   _| |_  __ _   |  Type "?help" for help.
4  | | | | | | |/ _` |  |
5  | | |_| | | | (_| |  |  Version 0.6.0 (2017-06-19 13:05 UTC)
6 _/ |\__'_|_|_|\__'_|  |  Official http://julialang.org/ release
7|__/                   |  x86_64-w64-mingw32

julia
1julia> Pkg.add("IJulia")
2ERROR: GitError(Code:ENOTFOUND, Class:Repository, Could not find repository from 'C:\Users\rk.julia\v0.6.cache\SHA')
3macro expansion at .\libgit2\error.jl:99 [inlined]
4Base.LibGit2.GitRepo(::String) at .\libgit2\repository.jl:10
5prefetch(::String, ::String, ::Array{String,1}) at .\pkg\cache.jl:41
6resolve(::Dict{String,Base.Pkg.Types.VersionSet}, ::Dict{String,Dict{VersionNumber,Base.Pkg.Types.Available}}, ::Dict{String,Tuple{VersionNumber,Bool}}, ::Dict{String,Base.Pkg.Types.Fixed}, ::Dict{String,VersionNumber}, ::Set{String}) at .\pkg\entry.jl:516
7resolve(::Dict{String,Base.Pkg.Types.VersionSet}, ::Dict{String,Dict{VersionNumber,Base.Pkg.Types.Available}}, ::Dict{String,Tuple{VersionNumber,Bool}}, ::Dict{String,Base.Pkg.Types.Fixed}) at .\pkg\entry.jl:479
8edit(::Function, ::String, ::Base.Pkg.Types.VersionSet, ::Vararg{Base.Pkg.Types.VersionSet,N} where N) at .\pkg\entry.jl:30
9(::Base.Pkg.Entry.##1#3{String,Base.Pkg.Types.VersionSet})() at .\task.jl:335
10Stacktrace:
11 [1] sync_end() at .\task.jl:287
12 [2] macro expansion at .\task.jl:303 [inlined]
13 [3] add(::String, ::Base.Pkg.Types.VersionSet) at .\pkg\entry.jl:51
14 [4] (::Base.Pkg.Dir.##4#7{Array{Any,1},Base.Pkg.Entry.#add,Tuple{String}})() at .\pkg\dir.jl:36
15 [5] cd(::Base.Pkg.Dir.##4#7{Array{Any,1},Base.Pkg.Entry.#add,Tuple{String}}, ::String) at .\file.jl:59
16 [6] #cd#1(::Array{Any,1}, ::Function, ::Function, ::String, ::Vararg{Any,N} where N) at .\pkg\dir.jl:36
17 [7] add(::String) at .\pkg\pkg.jl:117