Fix a bug in the build master (introduced in [289]) where multiple slaves matching the same target platform would potentially start the same build. This is done by setting the build to `IN_PROGRESS` as soon as the build initiation is sent, as opposed to when the slave accepts the build request.

[egg_info]
tag_build = dev
tag_svn_revision = true

[sdist]
formats = bztar, gztar, zip

[unittest]
test-suite = bitten.tests
xml-results = build/test-results.xml
coverage-summary = build/test-coverage.txt
coverage-dir = build/coverage