providers/docker: read the container ID properly

CHANGELOG.md

@@ -15,6 +15,7 @@ BUG FIXES:
   - providers/docker: Images built using `build\_dir` will more robustly
       capture the final image. [GH-4598]
   - providers/docker: NFS synced folders now work. [GH-4344]
+  - providers/docker: Read the created container ID more robustly.
   - 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/driver.rb

@@ -53,7 +53,7 @@ module VagrantPlugins
         run_cmd += params[:extra_args] if params[:extra_args]
         run_cmd += [image, cmd]
 
-        execute(*run_cmd.flatten, **opts, &block).chomp
+        execute(*run_cmd.flatten, **opts, &block).chomp.lines.last
       end
 
       def state(cid)