chg: downgrade "failed to read channel" from abortmsg to debugmsg If the server has an uncaught exception, it will exit without being able to write the channel information. In this case, the client is likely to complain about "failed to read channel", which looks inconsistent with original hg. This patch silences the error message and makes uncaught exception behavior more like original hg. It will help chg to pass test-fileset.t.

histedit: do not close stdin Closing stdin is unexpected by chgserver and is not a good idea generally. This patch refactors related code a bit and make sure stdin is not closed. It will make chg much happier on test-histedit*.t.

tests: reorder hg serve commands chg currently does not support hg serve -d. It has a quick path testing if the command is hg serve -d and fallbacks to hg if so. But the test only works if "serve" is the first argument since the test wants to avoid false positives (for example, "-r serve" is different). This patch reorders "hg server" commands in tests, making them chg friendly.