I encountered some bad autoconf behavior on Fedora Core 14.
Specifically, I was running ./configure . That script did a test for g++. g++ was not installed.
However, because of the new fallback behavior, which prints "Install package 'gcc-c++' to provide command 'g++'? [N/y]" when an unknown command is entered, ./configure did not detect the problem. Only later did it realize that g++ was not installed.
Here is what I think might be a problem:
[cmccabe@highcastle ceph]$ g++ bash: g++: command not found... Install package 'gcc-c++' to provide command 'g++'? [N/y] [cmccabe@highcastle ceph]$ echo $? 0
cheers, Colin McCabe