I am unable to reproduce the problem on ubuntu.  I created a small Wapp
application (derived from examples/fileupload.tcl) that adds a page named
"slow" that does a loop of 10 million iterations.  I ran that script with
"tclsh fileup1.tcl --server 8080" and then hit it with 20 continuous parallel
HTTP requests using "http_load".  Running this for 1000 requests produced no
errors.

I tried adding the patch, but the patch fails for CGI.  I did not attempt
to debug the patch.