busybox: on upgrade save busybox if it is the last shell
During a busybox upgrade on a ipk based system, it is possible
that busybox is the only shell in the system. During the uninstall
the alternative for /bin/sh is removed and everything after that
goes down hill.
* Add a check to verify if busybox is the shell, and save it to
the busyboxrm directory created in tmp. Then add an alternative
for /bin/sh that points to that busybox at the lowest priority.
* Add PATH to the busyboxrm directory using shell(as during an upgrade
busybox and its links are missing).
* When install over remove extra busybox if present.
deb and rpm are uneffected by the bug because they both drag in bash,
however neither upgrade seemed to have issue with the changes.
[YOCTO 13850]
Signed-off-by: Jeremy A. Puhlman <jpuhlman@mvista.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
