Random crashes after f6763ab98609

[John W. Eaton]

On  6-Feb-2011, Konstantinos Poulios wrote:

| Alternatively, I have prepared the attached patch that you could also
| try and see if it fixes the problem. Btw. wouldn't it be better to
| move all updating_* file scope flags into bool_properrty objects
| inside axes::properties like in the attached patch? Isn't it more
| straightforward?

I don't know whether it is better to have them as hidden properties,
but it might make sense to at least make them class members.  But
either way, they probably still need to be protected with
unwind_protect so that they will be reset properly if an interrupt
arrives while they are temporary set.

jwe