Messed-up error text: "Message has more than one translation for plural form 0.: Unknown syntax error"

[Jeroen T. Vermeulen]

Got this message in an error email from a failed import:

Message has more than one translation for plural form 0.: Unknown syntax error

This is the same basic problem as bug 315043. The error text is passed where the exception constructor expects a file name or line number. The mistake is in c.l.translationformat.translation_common_format.

I grep'ed and found no other instances of this problem with this exception class hierarchy. I wonder if there are ways to prevent this mistake though.