i18n: fix one i18n:msg in the error.html which didn't wrap all the needed tags.
We had to use a `<span i18n:msg="..." py:strip="">` instead of the more direct `<i18n:msg params="...">` in order to work around the #G385 issue.
Closes #9307.
Authored by: cboos 2010-05-07
Parent: [r9630]
Child: [r9632]
