[Plugin: W3 Total Cache] CDN URL rewriting regexp problem

I seem to have come up against an issue with the regular expressions in W3TotalCache’s ob_callback that replace local URLs for their counterparts in the CDN.

We are trying to implement an Azure CDN.

Because most of the content is managed by the MagicFields plugin, I have added wp-content/files_mf/* to the Custom file list.

If I enable debug, I see some strange characters appended to replaced URLS, for example, for this cached thumbnail:

/wp-content/files_mf/cache/th_ded8de6ef54c061a659828a26028150e_1175_aquat_draw_04.jpg' } => http://xxx.blob.core.windows.net/xxx/wp-content/files_mf/cache/th_ded8de6ef54c061a659828a26028150e_1175_aquat_draw_04.jpg' }

These extra characters “‘ }” should not be there.

Here is the bit of HTML that causes the problem:
<span class="img-stub { width: 176, height: 124, src: '/wp-content/files_mf/cache/th_ded8de6ef54c061a659828a26028150e_1175_aquat_draw_03.jpg' }"></span>

Is it possible that the regexps in ob_callback are not correctly parsing this (admittedly unusual) markup?

many thanks, Julian

http://wordpress.org/extend/plugins/w3-total-cache/