Determine if objects can be found in the object database from a short OID.
The full OID of the found object if just one is found.
The database to be searched for the given object.
A prefix of the id of the object to read.
The length of the prefix.
0 if found, GIT_ENOTFOUND if not found, GIT_EAMBIGUOUS if multiple matches were found, other value < 0 if there was a read error.