Handle CGI SSL detection via HTTPS environment better. Some servers send on/off, 0/1, yes/no, and may be upper or lower case. This fix will handle all of those permutations. It was inspired by the detection done in in some other wsgi python web applications I looked at.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg ci -Ama -d '1000000000 0'
echo b > b
hg branch b
hg ci -Amb -d '1000000000 0'
hg co -C 0

echo fast-forward
hg merge b
hg ci -Ammerge -d '1000000000 0'

echo bogus fast-forward should fail
hg merge b

echo done