If you going to do such blocking can we PLEASE finally find a way to set up a more informative error message for blocked user agents.
I have long ago lost track of how many people come to WP:VPT and other places complaining that they are trying to write a bot / script / etc., and it isn't working because they are using a blocked user agent (such as the default Python agent) and they don't understand what is wrong.
The current English error message text that I see from Python reads:
"Our servers are currently experiencing a technical problem. This is probably temporary and should be fixed soon. Please try again in a few minutes.
You may be able to get further information in the #wikipedia channel on the Freenode IRC network.
The Wikimedia Foundation is a non-profit organisation which hosts some of the most popular sites on the Internet, including Wikipedia. It has a constant need to purchase new hardware. If you would like to help, please donate.
If you report this error to the Wikimedia System Administrators, please include the details below.
Request: GET http://en.wikipedia.org/wiki/Cat, from 99.60.6.239 via sq77.wikimedia.org (squid/2.7.STABLE7) to () Error: ERR_ACCESS_DENIED, errno [No Error] at Tue, 16 Feb 2010 22:25:20 GMT"
Everything except the very last line of that is either irrelevant or wrong. And ERR_ACCESS_DENIED, though vaguely informative, provides no detail about what happened or how to do things properly.
This is bad enough for bot operators who are likely to be fairly intelligent people, but if we are going to give this to everyone with a missing user agent string too (which includes people behind poorly behaved proxies and people who use certain anonminizing software out of intense desire for "privacy"), then this kind of response really starts to send the wrong message.
-Robert Rohde