worker: flush messages written by child processes before exit
I found some child outputs were lost while testing the previous patch. Since
os._exit() does nothing special, we need to do that explicitly.
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved