[Trlog] Single character in exchange field

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I think I now understand why some of you think 6.73 is broken when
trying to enter exchanges manually into the exchange window in the
IARU.

It has to do with the bandmap.  If the bandmap is enabled, I believe
the bug will appear.  If it is disabled, it will work fine.

It also has to do with the setting of INITIAL EXCHANGE OVERWRITE.  
If this is FALSE, I think it will also be fine.

Working on a fix for 6.74.

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