\def\biburlxi#1;{\def\temp{#1}\ifx\temp\empty\expandafter\biburlxiii\else
\biburlxii#1,,\done\let\biburlxafter\biburlxi\expandafter\biburlxmunch\fi}
\def\biburlxii#1,{\def\temp{#1}\ifx\temp\empty\expandafter\biburlxiii\else
\def\biburlxi#1;{\def\temp{#1}\ifx\temp\empty\expandafter\biburlxiii\else
\biburlxii#1,,\done\let\biburlxafter\biburlxi\expandafter\biburlxmunch\fi}
\def\biburlxii#1,{\def\temp{#1}\ifx\temp\empty\expandafter\biburlxiii\else