Nevermind reproduced locally.
In your case the file will be /tmp/bk-install-failure.txt and it'll look something like this
thor:~ georgn$ cat /tmp/bk-install-failure.txt
dyld: Library not loaded: /opt/local/lib/liblz4.1.dylib
Referenced from: /Applications/BitKeeper.app/Contents/Resources/bitkeeper/bk
Reason: image not found
The problem is that our build machine has liblz4 installed and your machine does not...
We'll have to rebuild for you.