Template code written within comment borders (<!-- -->) is being expanded, when
entire page is substed to another one, and results in endless loop.

Example:

page "Lorem ispum" contains:
<!-- This is Lorem ispum page -->
<!-- To clear this page, use {{subst:/clear}} -->
blah blah
foo
bar

page "Lorem ispum/clear" contains:
<!-- This is Lorem ispum page -->
<!-- To clear this page, use {{subst:/clear}} -->

When saving {{subst:/clear}} in empty "Lorem ipsum" page, it expands the
template in comment and shows the <!-- WARNING: template loop detected -->
warning as well. So the result is like:

<!-- This is Lorem ispum page -->
<!-- To clear this page, use <!-- This is Lorem ispum page -->
<!-- To clear this page, use /clear<!-- WARNING: template loop detected --> -->

Version: unspecified
Severity: minor