Heading loses formatting when preceding newline is deleted

In the Confluence 4.x editor, when the newline preceding a heading is deleted, the heading is reformatted to plain text. For example, when I have this text in the editor (as if it were entered using wikitext):

h1. First heading
Some text
h2. Second heading
More text

When I do this:

• Place cursor at the beginning of the word "Some"
• Hold shift and press down-arrow
• Press delete

I expect to end up with this:

h1. First heading
h2. Second heading
More text

But instead I end up with this:

h1. First heading
Second heading
More text

The heading formatting is lost. This is inconsistent with at least two other scenarios: (1) Deleting a newline preceding a bulleted list, and (2) Deleting a newline preceding a block of preformatted text, both of which retain the formatting of the text that follows the newline, which is correct/expected behavior.

This problem however is not reproducible in IE9.