Current output parsing is language depending

Currently the concrete output of `du` depends on the current systems locale. For example in German it is `1234 insgesamt`, which doesn't match the regular expression. The change tries to fetch the first number on that line and discards everything after.

What I currently ask myself: Does this work without problems with non-bare repositories too, or does that include the size of the checkout? Shouldn't be the output of `git count-objects -v` more reliable?