fedora: remove sample.hgrc from shipped files sample.hgrc was long obsolete and was removed in 63ed188e3fc7.

config: propose some sample global config file An example of what could be suggested to the user as a global config file. Trying to be conservative here, and only suggesting the safest possible extensions. In addition to the user-level extensions, the blackbox extension is something a sysadmin might reasonable want to enable for every repo on the system.

config: give more fine-tuned sample hgrcs to this command The hgrc for user config is typically different from the hgrc at the system-wide or repository level. This patch provides different sample hgrcs for each level. Sometimes when copying repos around, the copy or the original don't have a default path yet, so at least for `hg config -l`, this ought to provide a more reasonable default and suggestions of what typically goes there. The actual sample configs go in the config.py file, to minimise clutter. In order to avoid an unnecessary import, the corresponding import for this dictionary is at the file level.

rebase: add a deprecated -i/--interactive flag A common mistake can be to type 'hg rebase -i' to discover interactive history editing. We add a -i/--interactive flag as discussed in the sprint and deprecate it right away, but hint people using it to use histedit instead.

revlog: introduce isancestor method for efficiently determining node lineage Hide the not so obvious use of commonancestorsheads.

clone: provide sample username = config entry in .hg/hgrc (issue4359) Some users clone from a server before ever running 'hg config --edit', so they don't see our helpful template for things like enabling the username. Attempt to give them some helpful guidance.