util: add safename function for generating safe names to rename to This function finds a name which does not clash with any other name in the manifest, and so can be used to safely rename a file. Differential Revision: https://phab.mercurial-scm.org/D783

merge: improve error messages for path conflicts during update Differential Revision: https://phab.mercurial-scm.org/D782

merge: check for path conflicts when updating (issue5628) When updating to a new revision, check for path conflicts caused by unknown files in the working directory, and handle these by backing up the file or directory and replacing it. Differential Revision: https://phab.mercurial-scm.org/D781

merge: rename conflicts to fileconflicts in _checkunknownfiles We will need to distinguish between file conflicts and path conflicts. Rename the conflicts variable so that it will be clearly distinct from pathconflicts, which will be introduced in a future commit. Differential Revision: https://phab.mercurial-scm.org/D780

merge: add _checkunknowndirs function for detecting path conflicts Add a new function which, given a file name, finds the shortest path for which there is a conflicting file or directory in the working directory. Differential Revision: https://phab.mercurial-scm.org/D779

merge: backup conflicting directories when getting files During batchget, if a target file conflicts with a directory, or if the directory a target file is in conflicts with a file, backup and remove the conflicting file or directory before performing the get. Differential Revision: https://phab.mercurial-scm.org/D778

merge: add merge action 'pr' to rename files during update Add a new merge action to handle a path conflict by renaming the conflicting file to a safe name. The rename is just to avoid problems on the filesystem. The conflict is still considered unresolved until the user marks the original path as resolved. Differential Revision: https://phab.mercurial-scm.org/D777

merge: add merge action 'p' to record path conflicts during update Add a new merge action to record path conflicts. A status message is printed, and the path conflict is added to the merge state. Differential Revision: https://phab.mercurial-scm.org/D776

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