Recreate repo state based on tagged file

Thank's for a nice package!

I could not find this, but perhaps this functionality already exists?

Basically, I think a nice functionality would be something like

function recreate_repo_state(file)
 d = load(file) 
 istagged(d) || throw(...)
 if ispatch(d)
  checkout_patch(d["commit"], d["patch"])
 else
  isdirty(d["commit"]) && @warn ...
  checkout(d["commit"])
 end

to allow easy reproducing of old results. The checkout function should be easy, but I'm not sure how to do the checkout_patch...

Additional related feature suggestions

• If packages with separate git-repos exists in src, also check these out to the tagged state
• Provide an easy mechanism such as reset_repo_state to go back to the current state (including repos in src)