Fix referring to deleted buffer, by deleting it

The comment explains, badly, that there is a bug somewhere that when we
wipe out the disassembly buffers, we end up with:

|| Caught exception in Test_Disassembly_Open_Close(): Vim(py3):vim.error: Vim(py3):vim.error: attempt to refer to deleted buffer

But I can't work out why exactly. Wiping out the buffer causes this, but
deleting the buffer doesn't.

Author: puremourning

python3/vimspector/debug_session.py

@@ -552,7 +552,7 @@ def SwitchFrom( self ):
 
   def OnChannelData( self, data ):
     if self._connection is None:
-      # Should _not_ happen, but maybe possible due to races or vim bufs?
+      # Should _not_ happen, but maybe possible due to races or vim bugs?
       return
 
     self._connection.OnData( data )

python3/vimspector/disassembly.py

@@ -173,7 +173,18 @@ def Reset( self ):
 
     self._buf = None
     for b in self._scratch_buffers:
-      utils.CleanUpHiddenBuffer( b )
+      # FIXME/TODO: Unknown hack :(
+      # For some reason I can't work out if the buffer is wiped out here, we
+      # get a test failure in Test_Disassembly_Open_Close.
+      # Initially I thought it was because _scratch_buffers might contain
+      # duplicates, but changing it to a set() doesn't help, so it's not that. 
+      # What seems to happen is we get data on the socket/channel and the
+      # callback tries to do something with the wiped-out buffer.
+      #
+      # Unfortunately I can't fathom what's happening, so hacking this
+      # wipeout=False for now to make the tests pass. Yes, I'll suffer in
+      # purgatory for that.
+      utils.CleanUpHiddenBuffer( b, wipeout=False )
 
     self._scratch_buffers = []
 

python3/vimspector/utils.py

@@ -161,14 +161,16 @@ def CleanUpCommand( session_id, name, api_prefix ):
       name ) )
 
 
-def CleanUpHiddenBuffer( buf ):
+def CleanUpHiddenBuffer( buf, wipeout=True ):
   if not buf.valid:
     return
 
+  cmd = 'bwipeout' if wipeout else 'bdelete'
+
   try:
-    vim.command( 'bwipeout! {}'.format( buf.number ) )
+    vim.command( '{}! {}'.format( cmd, buf.number ) )
   except vim.error as e:
-    if 'E517' not in str( e ):
+    if 'E517' not in str( e ) and 'E516' not in str( e ):
       raise