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

show: pass the minimum length for nodes as a template keyword This will allow us to make the displayed length configurable and/or dynamic. Differential Revision: https://phab.mercurial-scm.org/D556

cmdutil: allow extra properties to be added to each context The changeset displayer allows setting extra keywords to be available to the templating layer. This patch adds an argument to displaygraph() to pass a dict of extra properties to be available to every changeset. Differential Revision: https://phab.mercurial-scm.org/D555

dirstate: perform transactions with _map using single call, where possible This is in the same style as https://phab.mercurial-scm.org/D493. In general, this replaces patterns such as: ``` f in self._map: entry = self._map[f] ``` with: ``` entry = self._map.get(f): if entry is not None: # use entry ``` Test Plan: `make tests` Differential Revision: https://phab.mercurial-scm.org/D663

extensions: register config item early Config items are likely to be used in during extensions setup. So we much register them before that. For example this apply to the 'win32text.warn' options.

extensions: factor extra data loading out Some of the extra data need to be registered earlier than they currently are (eg: config items). We first factor out the logic to registered them in a small function before reusing it in the next changeset.

configitems: register the 'win32text.warn' config

configitems: register the 'mq.secret' config

configitems: register the 'mq.plain' config

configitems: register the 'mq.keepchanges' config