fix: commit obj hashes should all be 40 char long
- some were beginning with and not begin with
run git log with --topo-order for more consistent ordering
mostly for easier testing
add specific tests on contents of commit objects
fix: last commit obj incorrectly ending with commitSep
return for commits not at head of a branch, return empty branches array
make build paths and command configurable
build output dir if it doesn't already exist
isolate builds to avoid collisions between concurrent builds
add tests for builds