commandserver: attach prompt default and choices to message These attributes are important to provide a GUI prompt to user.

test-commandserver: clean up quoting and location of dbgui extension This helps embedding '$' in the script.

ui: extract helpers to write message with type or label This provides a 'type' attribute to command-server clients, which seems more solid than relying on 'ui.<type>' labels. In future patches, type='progress' will be added to send raw progress information.

commandserver: add experimental option to use separate message channel This is loosely based on the idea of the TortoiseHg's pipeui extension, which attaches ui.label to message text so the command-server client can capture prompt text, for example. https://bitbucket.org/tortoisehg/thg/src/4.7.2/tortoisehg/util/pipeui.py I was thinking that this functionality could be generalized to templating, but changed mind as doing template stuff would be unnecessarily complex. It's merely a status message, a simple serialization option should suffice. Since this slightly changes the command-server protocol, it's gated by a config knob. If the config is enabled, and if it's supported by the server, "message-encoding: <name>" is advertised so the client can stop parsing 'o'/'e' channel data and read encoded messages from the 'm' channel. As we might add new message encodings in future releases, client can specify a list of encoding names in preferred order. This patch includes 'cbor' encoding as example. Perhaps, 'json' should be supported as well.

commandserver: fix reference before assignment error in pipeservice cleanup Spotted by the next patch.

dispatch: pass around ui.fmsg channel This will be set by the command server. See the next patch.

test-subrepo: document why share magically works even if subrepos are missing I was confused how it's working while reviewing fb490d798be0, "share: reload repo after adjusting it in postshare()."

packaging: add Fedora 29 target Differential Revision: https://phab.mercurial-scm.org/D5254

store: pass in decoded filename to narrow matcher

test-narrow-clone-stream: include no usefncache case which is broken Since 9aeb9e2d28a7, encoded filenames are filtered by the narrow matcher, which is clearly wrong.