The problem, described by Udi, was the following:
See section 1.10 of babel's manual, on page 12 under
"TROUBLESHOOTING". There cannot be
a closing curly brace after a shorthand, and in babel-spanish
">" is a shorthand.
Thanks to Udi and Jürgen for the patch.
This is a more general fix than the (now reverted) fix at
fa67f709.
For ML discussion, see here:
https://www.mail-archive.com/search?l=mid&q=rwwvyyvwmx5wwvwhqdaioil32hblkzi7ghokzgekksrf66ww3f%40u6nj3guoayay
LangCode es_ES
PostBabelPreamble
\addto\shorthandsspanish{\spanishdeactivate{~<>}}
+ \deactivatequoting
EndPostBabelPreamble
End
LangCode es_MX
PostBabelPreamble
\addto\shorthandsspanish{\spanishdeactivate{~<>.}}
+ \deactivatequoting
EndPostBabelPreamble
End