Fix for 4824 - multi comments cause internal error

[davidBar-On]

Closes #4824

The suggested fix is in two code changes done for Version Two - by adding trim_start() before passing a comments string to rewrite_comment().

A more robust fix may be to do the trim_start() (or even trim()) inside rewrite_comment() (for Version Two), but I didn't evaluate the overall use of rewrite_comment() to make sure this is o.k.

[ytmimi]

For what it's worth, I had a similar idea of removing the leading whitespace in #5392.