Merge branch 'sb/unpack-trees-super-prefix'

"git read-tree" and its underlying unpack_trees() machinery learned
to report problematic paths prefixed with the --super-prefix option.

* sb/unpack-trees-super-prefix:
unpack-trees: support super-prefix option
t1001: modernize style
t1000: modernize style
read-tree: use OPT_BOOL instead of OPT_SET_INT

diff --cc git.c
Simple merge

diff --cc unpack-trees.c
Simple merge