In the bad old days of ASDF1, the few implementations that provided ASDF each provided their own patched version.
In the days of ASDF2, they all provide a baseline release, except when an urgent patch was required - but return to mainline at next release while mainline quickly merges in the patch. So it's only a matter of how current your ASDF is - don't use something older than what your implementation provides; something newer is encouraged if you need it.
ECL is an exception in that it also loads asdf-bundle (nee asdf-ecl) when you (require "asdf"). This tends to defeat quicklisp, but I'll fix that by merging asdf-bundle into asdf.
Yes, you can prevent Quicklisp from loading a bad ASDF simply by loading yours first. If you're using ECL, you should also load asdf-bundle immediately afterwards.
In the bad old days of ASDF1, the few implementations that provided ASDF each provided their own patched version.
In the days of ASDF2, they all provide a baseline release, except when an urgent patch was required - but return to mainline at next release while mainline quickly merges in the patch. So it's only a matter of how current your ASDF is - don't use something older than what your implementation provides; something newer is encouraged if you need it.
ECL is an exception in that it also loads asdf-bundle (nee asdf-ecl) when you (require "asdf"). This tends to defeat quicklisp, but I'll fix that by merging asdf-bundle into asdf.
Yes, you can prevent Quicklisp from loading a bad ASDF simply by loading yours first. If you're using ECL, you should also load asdf-bundle immediately afterwards.