ida-minsc: ReadOrWriteError exception raised when trying to use comment api in IDA 6.8

This issue manifested after fixing issue #59 with PR #60 (some prior conversation exists in those tickets, so start there if you need context for this).

Python>db.comment(0x006DA9CF, "123")
CRITICAL:root:internal.interface.priorityhook.callback(7186895, False) : Callback for "IDB_Hooks.cmt_changed" with priority (+0) raised an exception while executing <bound method type.old_changed of <class 'hooks.address'>>
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : Traceback ("IDB_Hooks.cmt_changed" was hooked at)
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : File "C:\Users\Hskyre\AppData\Roaming\Hex-Rays\IDA Pro\misc\hooks.py", line 1059, in ida_is_busy_sucking_cocks
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : make_ida_not_suck_cocks(idaapi.NW_INITIDA)
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : File "C:\Users\Hskyre\AppData\Roaming\Hex-Rays\IDA Pro\misc\hooks.py", line 993, in make_ida_not_suck_cocks
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : ui.hook.idb.add('cmt_changed', address.old_changed, 0)
WARNING:root:internal.interface.priorityhook.callback(7186895, False) :
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : Traceback (most recent call last):
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : File "C:\Users\Hskyre\AppData\Roaming\Hex-Rays\IDA Pro\base_interface.py", line 373, in closure
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : result = callable(*parameters)
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : File "C:\Users\Hskyre\AppData\Roaming\Hex-Rays\IDA Pro\misc\hooks.py", line 219, in old_changed
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : internal.comment.contents.set_address(ea, 0)
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : File "C:\Users\Hskyre\AppData\Roaming\Hex-Rays\IDA Pro\base_comment.py", line 971, in set_address
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : raise internal.exceptions.ReadOrWriteError(u"{:s}.set_address({:#x}, {:d}{:s}) : Unable to write name to address {:#x}.".format('.'.join(('internal', name, cls.name)), address, count, ', {:s}'.format(internal.utils.string.kwargs(target)) if target else '', address))
WARNING:root:internal.interface.priorityhook.callback(7186895, False) : ReadOrWriteError: internal.comment.contents.set_address(0x6da9cf, 0) : Unable to write name to address 0x6da9cf.
WARNING:root:internal.interface.priorityhook.callback(7186895, False) :