commands: update the resolve command to handle path conflicts The resolve command must support displaying path conflicts and marking them as resolved or unresolved. Differential Revision: https://phab.mercurial-scm.org/D775

merge: add pathconflict merge state Path conflicts that occur during merges are represented by 'pu' (unresolved) and 'pr' (resolved) records in the merge state. These are stored on disk in 'P' records. Differential Revision: https://phab.mercurial-scm.org/D774

tests: add a test demonstrating basic path conflict failures Differential Revision: https://phab.mercurial-scm.org/D773

scmutil: handle conflicting files and dirs in origbackuppath When ui.origbackuppath is set, .orig files are stored outside of the working copy. However conflicts can occur when files or directories end up having the same name. These conflicts cause Mercurial to abort, even if they've been created as a result of different backups. Make sure we always replace files or directories in the origbackuppath if they conflict with another file or directory. Test Plan: Add new unit test for conflicting paths. Differential Revision: https://phab.mercurial-scm.org/D680

extdata: show debug message if external command exits with non-zero status This isn't fatal because it's quite common for grep to exit with 1. Thanks to Foozy for spotting this.

templatekw: allow accessing to nested namespace item by its template name Since we have the dot operator, it makes more sense to write {namespaces.tags % "{tag}"} instead of {namespaces.tags % "{name}"}

templatekw: get rid of temporary dicts from shownamespaces()