communicators/ssh: handle closed connection without exception

CHANGELOG.md

@@ -12,6 +12,7 @@ IMPROVEMENTS:
 
   - core: add `--color` to any Vagrant command to FORCE color output. [GH-2027]
   - core: "config.vm.host_name" works again, just an alias to hostname.
+  - core: Reboots via SSH are now handled gracefully (without exception).
   - commands/plugin/install: Post install message of a plugin will be
     shown if available. [GH-1986]
   - commands/status: cosmetic improvement to better align names and

plugins/communicators/ssh/communicator.rb

@@ -359,7 +359,12 @@ module VagrantPlugins
           end
 
           # Wait for the channel to complete
-          channel.wait
+          begin
+            channel.wait
+          rescue IOError
+            @logger.info("SSH connection unexpected closed. Assuming reboot or something.")
+            exit_status = 0
+          end
         ensure
           # Kill the keep-alive thread
           keep_alive.kill if keep_alive