patch 8.1.1524: tests are silently skipped

Problem:    Tests are silently skipped.
Solution:   Throw an exception for skipped tests in more places.

src/testdir/test_paste.vim

@@ -1,8 +1,11 @@
 " Tests for bracketed paste and other forms of pasting.
 
 " Bracketed paste only works with "xterm".  Not in GUI or Windows console.
-if has('gui_running') || has('win32')
-  finish
+if has('win32')
+  throw 'Skipped, does not work on MS-Windows'
+endif
+if has('gui_running')
+  throw 'Skipped, does not work in the GUI'
 endif
 set term=xterm
 
@@ -122,7 +125,6 @@ func Test_xrestore()
   if !has('xterm_clipboard')
     return
   endif
-call ch_logfile('logfile', 'w')
   let display = $DISPLAY
   new
   call CheckCopyPaste()
@@ -133,6 +135,5 @@ call ch_logfile('logfile', 'w')
   exe "xrestore " .. display
   call CheckCopyPaste()
 
-call ch_logfile('', '')
   bwipe!
 endfunc