manifest_version_unittest: fix breakage from conflicting revs
manifest_version_unittest: fix breakage from conflicting revs

Via I8997ad68bb697bbba3707755ae4cb22cfcb31f18 and
Icbe20fcab363af0ddda83d8a3385f296c7571d00, the GIT_DIR cleanup
was partially merged; end result being this test breaking.

BUG=None
TEST=python manifest_version_unittest.py

Change-Id: Ie006ba9c3000569f8f70e079e6d34ca4287cfe13
Reviewed-on: https://gerrit.chromium.org/gerrit/13971
Commit-Ready: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Tested-by: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>

chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,zhang0137/chromite,zhang0137/chromite,chadversary/chromiumos.chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,coreos/chromite