ui: allow capture of subprocess output We want to capture hooks output during bundle2 processing. For this purpose we introduce a new 'subproc' argument to 'ui.pushbuffer'. When set, the output of sub process created through 'ui.system' will be captured in the buffer too. This will be used in the next changeset.

bundle2: capture transaction rollback message output (issue4614) The output from the transaction rollback was not included into the reply bundle. It was eventually caught by the usual 'unbundle' output capture and sent to the client but the result was out of order on the client side. We now capture the output for the transaction release and transmit it the same way as all other output. We should probably rethink the whole output capture things but this would not be appropriate for stable. The is still multiple cases were output failed to be properly capture, they will be fixed in later changesets.

bundle2: issue remote output as "status" (issue4612) Remote output should be silenced by --quiet. The issue was found while running `test-largefiles-cache.t` so it will get tested once we switch bundle2 by default.

record: edit patch of newly added files (issue4304) I tried to fix this issue in the past and had to revert the fix. This is a second attempt without the regression we found with the first one. record defines special headers (of file) as headers whose hunk are not shown to the user for editing, they are used to represent deleted, moved and new files. Since we want to authorize editing the patch of newly added file we make the newly added file with some content not special anymore. This entails that we have to save their content before applying the backup to be able to revert it if the patch does not apply properly. We reintroduce the test showing that newly added files can be edited and that their content is shown to the user.