Perform a local clone into a repository
A "local clone" bypasses any git-aware protocols and simply copies over the object database from the source repository. It is often faster than a git-aware clone, but no verification of the data is performed, and can copy over too much data.
the branch to checkout after the clone, pass NULL for the remote's default branch
wether to use hardlinks instead of copying objects. This is only possible if both repositories are on the same filesystem.
0 on success, any non-zero return value from a callback function, or a negative value to indicate an error (use giterr_last
for a detailed error message)