SLIME completion does not complete up to first non-unique point in string

[sjamaan]

When I type in (with-i<TAB>), I'd expect SLIME to complete (with-input-from-) and then offer me the options with-input-from-file, with-input-from-port, with-input-from-string and with-input-from-pipe.

Right now it only offers options for completion but does not fill out the parts that can already be filled out, requiring me to switch to the completion buffer and choose an option or type it out myself until there's only one option left; this it does complete.

According to Christian, this may be a problem with the way the swank server replies to the completions request.