pager: rename variables of backup fds The next patch will add backup file objects, so the original variable names would be confusing.

pager: inline _pagersubprocess() into _runpager() We don't need _pagersubprocess() because the fork version was removed at 59d794154e8d.

ui: send traceback of devel warning to appropriate output stream If ui.ferr is a command-server channel, traceback should be written to it.

util.system: compare fileno to see if it needs stdout redirection Future patches will reopen stdout to be line-buffered, so sys.stdout may be different object than sys.__stdout__.

exchange: move stream clone logic into pull code path Stream clones are a special case of clones. Clones are a special case of pull. Most of the logic for deciding what to do at pull time is in exchange.py. It makes sense for the stream clone determination to live there as well. This patch moves the calling of the stream clone code into pull(). The checks in streamclone.canperformstreamclone() ensure that we don't perform a stream clone unless it is possible. A future patch will convert maybeperformstreamclone() to accept a pullop to make it consistent with everything else in pull(). It will also grow some functionality (in case you doubted the necessity of a 4 line function).

exchange: teach pull about requested stream clones An upcoming patch will move the invocation of stream cloning logic to the normal pull code path (from localrepository.clone). In preparation for this, we teach pull() and pulloperation about whether a streaming clone is requested. The return logic in localrepository.clone() has been reformatted slightly because of line length issues.