Fix indentation for comments

[patnr]

As indicated by this comment the intent is to apply the indent of the preceding line, not the current.

Without this patch, the code

        \begin{equation}
                  a = b \\
                  % comment
                  c = d
        \end{equation}

Gets indented (for example with vie=) to

        \begin{equation}
          a = b \\
                  % comment
          c = d
        \end{equation}

With the patch I get

        \begin{equation}
          a = b \\
          % comment
          c = d
        \end{equation}

[lervag]

Sorry about the delay - I've been on vacations.

This looks like a very good catch, thanks!