If you get this error message:

Can't exec "autopoint": No such file or directory at /usr/share/autoconf/Autom4te/FileUtils.pm

Then, you need to install autopoint:

sudo aptitude install autopoint

I ran into this while building ledger today and had never needed to do that before. The error that acprep provides is even more cryptic:

Automatically preparing build ... Warning: autoreconf failed

Then, I ran autogen.sh and the autpoint error showed up.