Why does WordPress get posts from MySQL from a virtual hostname but not the direct hostname?

I’m developing a WordPress site on my Mac, running OS X 10.6.4. I’m using OS X’s built-in Apache server to run the site locally during development. I’ve set up WordPress and connected it to OS X’s MySQL with no problems. The site seems to work fine, and I can post, edit, etc.

The WordPress installation is in a folder called ~/Sites/mysite.dev.

I’ve also customized my .hosts file and Apache’s httpd-vhosts.conf file, to redirect requests for mysite.dev to this folder. So when I enter http://mysite.dev in a browser window, the site loads. No problems here.

So I can access the site, in a browser, from two different addresses, http://mysite.dev, and http://localhost/~Gabe/mysite.dev/.

Here’s what’s weird: When I go to http://mysite.dev, the WordPress site loads normally. When I go to http://localhost/~Gabe/mysite.dev/, WordPress can’t find any posts from the database: It gives me the “Sorry, no posts met your criteria” message (which is built into the theme for when a search for posts returns nothing). N.B.: Apache processes the PHP code normally in both cases — but in one case WordPress can get posts from MySQL, and in the other case it can’t.

My first thought was that this was a problem with WordPress’s configuration, so I changed the WordPress URL to http://localhost/~Gabe/mysite.dev/, but this made no difference.

I don’t understand why using the two addresses produces different results. Any help appreciated.

(Here’s why I care, in case you’re wondering: I want to preview the site in BBEdit’s web preview window, and BBEdit will only load the site via the http://localhost/~Gabe/mysite.dev/ address.)