Actually I found a solution by looking in the code for the tiny_mce_config file.
I replaced
'relative_urls' => false,
with
'relative_urls' => true,
Which allows me to do exactly what I wanted to do, and I can change it back later.
I can see the valid argument for using absolute urls. But is there a way to disable the “forced absolute urls” in 2.5? It is proving cumbersome for editing older posts, and I would like to be able to stick with relative links at least temporarily.
