convert: encapsulate commit data fetching and commit object creation
Split fetching the `describe` form from Perforce and the commit object creation
into two functions. This allows us to reuse the commit construction for
revisions passed from a revmap.
FROM debian:jessie
RUN apt-get update && apt-get install -y \
build-essential \
debhelper \
dh-python \
devscripts \
python \
python-all-dev \
python-docutils \
zip \
unzip