This starts at the "core.abbrev" length (default 7 characters) and
iteratively extends to a longer string if that length is ambiguous.
The result will be unambiguous (at least until new objects are added to
the repository).
@param out_ Buffer to write string into
@param obj The object to get an ID for
@return 0 on success, <0 for error
Get a short abbreviated OID string for the object
This starts at the "core.abbrev" length (default 7 characters) and iteratively extends to a longer string if that length is ambiguous. The result will be unambiguous (at least until new objects are added to the repository).
@param out_ Buffer to write string into @param obj The object to get an ID for @return 0 on success, <0 for error