intertext problem

[kozyakin]

Comparing the following two files containing \intertext in align* environment I obtain correct comparison for the first align* environment and erroneous one for the second (with incorrect string \DIFadd{\intertext{whereas}):

file #1

\documentclass{article}
\usepackage{amsmath}

\begin{document}

First align environment:
\begin{align*}
a&=b\
\intertext{whereas}
b&=c
\end{align*}

Second align environment:
\begin{align*}
a&=b\
\intertext{whereas}
b&=c
\end{align*}
\end{document}

file #2

\documentclass{article}
\usepackage{amsmath}

\begin{document}

First ``align'' environment:
\begin{align*}
a&=b\
\intertext{where}
b&=c
\end{align*}

Second ``align'' environment is empty.

\end{document}

Probably the problem caused by the fact that the second align' environment in file #1 matches to nothing.