shortest: don't keep checking for longer prefix if node doesn't exist (API) If revlog.shortest() is called with an invalid nodeid, we keep checking if longer and longer prefixes are valid. We call revlog._partialmatch() for each prefix. That function will give us None if the node doesn't exist (and a RevlogError if it's ambiguous), so there's no need to keep checking. This patch instead makes revlog.shortest() raise a LookupError is the node does not exist, and updates the caller to handle it. Before this patch, revlog.shortest() would return the full hexnode for nonexistent nodeids. By the same reasoning as in 7b2955624777 (scmutil: make shortesthexnodeidprefix() take a full binary nodeid, 2018-04-14), it's not revlog.shortest() that should decide how to present nonexistent nodeids, so that's now moved to the template function. This should speed up cases where {shortest()} is applied to an invalid nodeid, but I couldn't think of a reasonable case where that would happen. Differential Revision: https://phab.mercurial-scm.org/D3461

shortest: extract function for checking if a prefix is a revnum Much of isvalid() was about testing if a prefix is a valid revnum. I want to reuse that soon, so let's move it out. There is no significant slowdown from the function call overhead. Differential Revision: https://phab.mercurial-scm.org/D3460

shortest: rename "test" variable to "prefix" Sorry if this is considered churn, but "prefix" just seems much clearer to me. Differential Revision: https://phab.mercurial-scm.org/D3459

shortest: move some safe code out of exception block The RevlogError and WdirUnsupported could be raised by _partialmatch(), but not by the rest of isvalid(), so let's move the rest out to make it clearer. Differential Revision: https://phab.mercurial-scm.org/D3458

revlog: don't say "not found" on internal error If index_node() returned NULL, then index_find_node() and and nt_partialmatch() used to return -2 to signal that the node was not found. However, we were passing in a revnum to index_node() that we knew should exist, so the only reason it could return NULL was due to some internal error or perhaps out of memory. Let's not use "not found" for these cases. I suppose we never noticed this because these error never happen in practice. I think there are more places where we should error out instead of reporting that the node was not found, but the cases mentioned above were all I cared about right now (because using the same error code for all failures simplified some future patches). Differential Revision: https://phab.mercurial-scm.org/D3457

revlog: extract function for getting node from known-to-exist rev Many of the calls to index_node() (which converts a rev to a nodeid) are done with a rev that's know to exist. If the function fails, there's something really wrong and we should just abort. This was done in only one place. This patch starts by extracting that code to a function that we can reuse in later patches. Differential Revision: https://phab.mercurial-scm.org/D3456

shortest: make {shortest("fffffffff")} work again {shortest("fffffffff")} should shorten it to the shortest unambiguous prefix for the working directory. It used to do that until I broke it in 7b2955624777 (scmutil: make shortesthexnodeidprefix() take a full binary nodeid, 2018-04-14), when we started returning the full hex nodeid for any working directory prefix shorter than 40 hex digits. This patch fixes it by catching WdirUnsupported specifically. Differential Revision: https://phab.mercurial-scm.org/D3455