You need git, and bazaar obviously. Also install bzr-fastimport, it contains the export plugin as well. The rest is a rip off from the folloing URL: http://fthieme.net/en/drupal6/node/77

git init project.git
cd project.git
bzr fast-export --export-marks=.git/bzr.mark ~/project.bzr | git fast-import --export-marks=.git/git.mark

That worked for me. The output will likely be something like this:

01:41:19 Calculating the revisions to include ...
01:41:19 Starting export of 33 revisions ...
01:41:20 Exported 33 revisions in 0:00:01
git-fast-import statistics:
---------------------------------------------------------------------
Alloc'd objects:         5000
Total objects  :          267 (         0 duplicates                  )
        blobs  :          158 (         0 duplicates         57 deltas)
        trees  :           76 (         0 duplicates         55 deltas)
        commits:           33 (         0 duplicates          0 deltas)
        tags   :            0 (         0 duplicates          0 deltas)
Total branches :           10 (         1 loads     )
        marks  :         1024 (        33 unique    )
        atoms  :           38
Memory total   :         2344 KiB
        pools  :         2110 KiB
        objects:          234 KiB
---------------------------------------------------------------------
pack_report: getpagesize()            =       4096
pack_report: core.packedGitWindowSize = 1073741824
pack_report: core.packedGitLimit      = 8589934592
pack_report: pack_used_ctr            =        267
pack_report: pack_mmap_calls          =         73
pack_report: pack_open_windows        =          1 /          1
pack_report: pack_mapped              =     977484 /     977484
---------------------------------------------------------------------

Now just do a simple git checkout master to get started working again.