Perform an operation on each reference in the repository
The processed references may be filtered by type, or using
a bitwise OR of several types. Use the magic value
GIT_REF_LISTALL
to obtain all references, including
packed ones.
The callback
function will be called for each of the references
in the repository, and will receive the name of the reference and
the payload
value passed to this method.
Filtering flags for the reference listing.
Function which will be called for every listed ref
Additional data to pass to the callback
0 or an error code