show: use consistent (and possibly shorter) node lengths `hg show` makes heavy use of shortest() to limit the length of the node hash. For the "stack" and "work" views, you are often looking at multiple lines of similar output for "lines" of work. It is visually appeasing for things to vertically align. A naive use of {shortest(node, N)} could result in variable length nodes and for the first character of the description to vary by a column or two. We implement a function to determine the longest shortest prefix for a set of revisions. The new function is used to determine the printed node length for all `hg show` views. .. feature:: show: use consistent node length in views Our previous shortest node length of 5 was arbitrarily chosen. shortest() already does the work of ensuring that a partial node isn't ambiguous with an integer revision, which is our primary risk of a collision for very short nodes. It should be safe to go with the shortest node possible. Existing code is also optimized to handle nodes as short as 4. So, we decrease the minimum hash length from 5 to 4. We also add a test demonstrating that prefix collisions increase the node length. .. feature:: show: decrease minimum displayed hash length from 5 to 4 Differential Revision: https://phab.mercurial-scm.org/D558