patch 8.0.0547: extra line break in verbosefile

Problem:    Extra line break in verbosefile when using ":echomsg". (Ingo
            Karkat)
Solution:   Don't call msg_start(). (closes #1618)
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 1b0597e..3295912 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -412,4 +412,14 @@
   cunmap <F6>
 endfunc
 
+func Test_verbosefile()
+  set verbosefile=Xlog
+  echomsg 'foo'
+  echomsg 'bar'
+  set verbosefile=
+  let log = readfile('Xlog')
+  call assert_match("foo\nbar", join(log, "\n"))
+  call delete('Xlog')
+endfunc
+
 set cpo&