buffer-invisibility-spec isn't a list

[Oleg Sivokon <olegsivokon@gmail.com>]

In the function `org-move-to-column' when you call (remove
'(org-filtered) buffer-invisibility-spec) it is quite possible that
`buffer-invisibility-spec' is just `t'.  This will error, because
`remove' expects second argument to be a list.

This happens when opening Babel code blocks in a special editing buffer
(thus <C-c '> will not be set for them).

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(defun org-move-to-column (column &optional force buffer)
  "Move to column COLUMN.
Pass COLUMN and FORCE to `move-to-column'.
Pass BUFFER to the XEmacs version of `move-to-column'."
  (let ((buffer-invisibility-spec
         (if (eq t buffer-invisibility-spec) t
           (remove '(org-filtered) buffer-invisibility-spec))))
    (if (featurep 'xemacs)
        (org-xemacs-without-invisibility
         (move-to-column column force buffer))
      (move-to-column column force))))
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Seems to fix it.

Best.

Oleg