EPS preview lost on resave

[John Gamelin]

Hi:

I have noticed that the EPS preview seems to get lost whenever I re-export a
figure after making changes.  The first export works fine but if I make any
changes and re-export to the same filename it is permanently lost.  If I
change the name of the file to export to it works fine.

I have noticed this since 4.0 (the first version I used) and it has gotten
annoying enough to post.  Any insights would be appreciated.

Thanks.

John