I found out that to build a B2G pine i have to install mercuial on OSX manualy. It was not in the https://developer.mozilla.org/en-US/docs/Mozilla/B2G_OS/B2G_OS_build_prerequisites site so i added it.
Im not shure if thats the right place. Im no Programer nor do i have skills about how the doc should be organised. So somebody should have an eye on it maybe…
and this one as well: https://developer.mozilla.org/en-US/docs/Mozilla/B2G_OS/Preparing_for_your_first_B2G_build
from vim ~/.gitconfig away…