devel/cargo-c and devel/libgit2 leave work directories

[John Klos <john%klos.com@localhost>]

I've been noticing that even when pkg_rolling-replace successfully 
completes (in a tmux session, because of Python), it sometimes leaves work 
directories around.

Anyone know why this is? I just did an update and pkg_rolling-replace and 
have devel/cargo-c and devel/libgit2 work directories on two different 
machines.

Anyone want logs?

John