scmutil: make shortesthexnodeidprefix() take a full binary nodeid The shortest() template function depended on the behavior of revlog._partialmatch() for these types of inputs: * non-hex strings * ambiguous strings * too long strings revlog._partialmatch() seems to return the input unchanged in these cases, but we shouldn't depend on such a low-level function to match the behavior we want in the user-facing template function. Instead, let's handle these cases in the template function and always pass a binary nodeid to _partialmatch(). Differential Revision: https://phab.mercurial-scm.org/D3371