well, (kinda) backport LimitInternalRecursion. This prevents the server from crashing if someone configure an infinite loop of internal redirects and subrequests. Default value is 20/20 (subsequent redirects/nested subrequests), 0 means unlimited.
The patch works fine on my box, but is required to be tested extensively before the next release.
PR: 19753 (and probably more) Obtained from: 2.0 patch Reviewed by: original 2.0 port by Justin and BrianP (?)