communicators/ssh: cleaner error if remote disconnect [GH-4038]

CHANGELOG.md

@@ -27,6 +27,7 @@ BUG FIXES:
   - core: Fix crash case when destroying with an invalid provisioner. [GH-4281]
   - commands/package: base package won't crash with exception [GH-4017]
   - commands/rsync-auto: Destroyed machines won't raise exceptions. [GH-4031]
+  - communicators/ssh: Nicer error if remote unexpectedly disconects. [GH-4038]
   - communicators/winrm: Support `mkdir` [GH-4271]
   - guests/centos: Fix issues when NFS client is installed by restarting
       NFS [GH-4088]

plugins/communicators/ssh/communicator.rb

@@ -517,8 +517,11 @@ module VagrantPlugins
           begin
             channel.wait
           rescue Errno::ECONNRESET, IOError
-            @logger.info("SSH connection unexpected closed. Assuming reboot or something.")
+            @logger.info(
+              "SSH connection unexpected closed. Assuming reboot or something.")
             exit_status = 0
+          rescue Net::SSH::Disconnect
+            raise Vagrant::Errors::SSHDisconnected
           end
         ensure
           # Kill the keep-alive thread