Merge branch 'tb/unexpected'

Code tightening against a "wrong" object appearing where an object of a different type is expected, instead of blindly assuming that the connection between objects are correctly made. * tb/unexpected: rev-list: detect broken root trees rev-list: let traversal die when --missing is not in use get_commit_tree(): return NULL for broken tree list-objects.c: handle unexpected non-tree entries list-objects.c: handle unexpected non-blob entries t: introduce tests for unexpected object types t: move 'hex2oct' into test-lib-functions.sh