Always remove credentials file after mount attempts

plugins/guests/linux/cap/mount_smb_shared_folder.rb

@@ -46,7 +46,7 @@ SCRIPT
 
           # Attempt to mount the folder. We retry here a few times because
           # it can fail early on.
-
+          begin
             retryable(on: Vagrant::Errors::LinuxMountFailed, tries: 10, sleep: 2) do
               no_such_device = false
               stderr = ""
@@ -63,6 +63,11 @@ SCRIPT
                   output: stderr
               end
             end
+          ensure
+            # Always remove credentials file after mounting attempts
+            # have been completed
+            machine.communicate.sudo("rm /etc/smb_creds_#{name}")
+          end
 
           emit_upstart_notification(machine, expanded_guest_path)
         end

test/unit/plugins/guests/linux/cap/mount_smb_shared_folder.rb

@@ -63,6 +63,11 @@ describe "VagrantPlugins::GuestLinux::Cap::MountSMBSharedFolder" do
       cap.mount_smb_shared_folder(machine, mount_name, mount_guest_path, folder_options)
     end
 
+    it "removes the credentials file before completion" do
+      expect(comm).to receive(:sudo).with(/rm.+smb_creds_.+/)
+      cap.mount_smb_shared_folder(machine, mount_name, mount_guest_path, folder_options)
+    end
+
     it "sends upstart notification after mount" do
       expect(comm).to receive(:sudo).with(/emit/)
       cap.mount_smb_shared_folder(machine, mount_name, mount_guest_path, folder_options)