svn does not match expected url

Today I tried to 'svn update' a very old folder from a very old repository
and got the error
     svn does not match expected url
I read about some related problems where it was pointed out that the
problem comes from an inconsistent use of upper and lower case in
windows and linux machines. However, in my case, both the repository
and the folder were on linux machines. Nevertheless, the repository is
in a machine which is listed in my /etc/hosts and thus has an abbreviated
name. Its full name is em.fis.unam.mx and its short name is em, so I
sometimes use
    svn ... svn://em.fis.unam.mx/...
and sometimes just
    svn ... svn://em/...

I checked manually that my folder was up to date and then removed it
to check out a fresh copy, so now I cannot reproduce the error.

Nevertheless, my questions are: Is this a known issue? Should I always
use the full name of the repository host? Is there a decent way to
correct the problem (in case it appears again in the future)?

Thanks and best regards,
Luis

-- 
                                                                  o
W. Luis Mochán,                      | tel:(52)(777)329-1734     /<(*)
Instituto de Ciencias Físicas, UNAM  | fax:(52)(777)317-5388     `>/   /\
Apdo. Postal 48-3, 62251             |                           (*)/\/  \
Cuernavaca, Morelos, México          | mochan_at_fis.unam.mx   /\_/\__/
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