the PLIST_CWD in creating the tar pipe.
This takes care of pkg_create -p PREFIX -L FAKE
where PREFIX does not exist at pkg creation time.
From OpenBSD's rev. 1.9->1.10
* Register PLIST_SRC before dependencies and conflicts so that the
PLIST_CWD != PLIST_SRC hack works with dependencies present.
From OpenBSD's rev. 1.10->1.11
* improve error message to tell full path of exec() that failed
f990f4a5a2