/usr/bin/git-clang-format-6.0 is in clang-format-6.0 1:6.0-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/../lib/llvm-6.0/bin/git-clang-format
/usr/bin/../lib/llvm-6.0/bin/git-clang-format