Bugfix: Start /bin/sh if /bin/bash does not exist in target_root
Bugfix: Start /bin/sh if /bin/bash does not exist in target_root

- /bin/bash is still the default.

loganchien/scratchbox2,OlegGirko/ldbox,loganchien/scratchbox2,BinChengfei/scratchbox2,h113331pp/scratchbox2,madscientist42/scratchbox2,BinChengfei/scratchbox2,madscientist42/scratchbox2,h113331pp/scratchbox2,OlegGirko/ldbox,madscientist42/scratchbox2,madscientist42/scratchbox2,loganchien/scratchbox2,ldbox/ldbox,lbt/scratchbox2,loganchien/scratchbox2,h113331pp/scratchbox2,loganchien/scratchbox2,madscientist42/scratchbox2,OlegGirko/ldbox,ldbox/ldbox,BinChengfei/scratchbox2,h113331pp/scratchbox2,ldbox/ldbox,BinChengfei/scratchbox2,lbt/scratchbox2,h113331pp/scratchbox2,madscientist42/scratchbox2,h113331pp/scratchbox2,OlegGirko/ldbox,BinChengfei/scratchbox2,ldbox/ldbox,OlegGirko/ldbox,OlegGirko/ldbox,lbt/scratchbox2,loganchien/scratchbox2,ldbox/ldbox,lbt/scratchbox2,ldbox/ldbox,BinChengfei/scratchbox2,lbt/scratchbox2