cd
git clone git://repo.or.cz/fast-export.git
git init git_repo
cd git_repo
~/fast-export/hg-fast-export.sh -r /path/to/old/mercurial_repo
git checkout HEAD

[extensions]
hggit =

$ mkdir git-repo; cd git-repo; git init; cd ..
$ cd hg-repo
$ hg bookmarks hg
$ hg push ../git-repo

$ cd git-repo
$ git checkout -b master hg

pip install gitifyhg
git clone gitifyhg::<hgrepoaddress>
# done, you have a git repo with the entire history of the hg one