Bug 8350: warning in logs when searching for nonexistent ISBN

Bug 8350: warning in logs when searching for nonexistent ISBN

Searching for a 10 or 13 digit numeric string that does not exist in
one's catalog will fail to affect SQL statement correctly
in C4::Breeding. Moved string substitution, which was triggering error
when search was undefined, and fixed if statements accordingly.

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>