providers/docker: expand vagrant_vagrantfile [GH-4000]

CHANGELOG.md

@@ -18,6 +18,7 @@ BUG FIXES:
   - providers/docker: Read the created container ID more robustly.
   - providers/docker: `vagrant share` uses correct IP of proxy VM if it
       exists. [GH-4342]
+  - providers/docker: `vagrant\_vagrantfile` expands home directory. [GH-4000]
   - providers/virtualbox: Show a human-friendly error if VirtualBox didn't
       clean up an existing VM. [GH-4681]
   - provisioners/docker: Search for docker binary in multiple places. [GH-4580]

plugins/providers/docker/provider.rb

@@ -73,6 +73,10 @@ module VagrantPlugins
           host_machine_name = :default
         end
 
+        # Expand it so that the home directories and so on get processed
+        # properly.
+        vf_path = File.expand_path(vf_path, @machine.env.root_path)
+
         vf_file = File.basename(vf_path)
         vf_path = File.dirname(vf_path)