rebase: also restore "ui.allowemptycommit" value It looks like this was lost when the code was converted to the ui.configoverride() context manager in f255b1811f5e (rebase: get rid of ui.backupconfig, 2017-03-16). (And then the bad example was duplicated in 228916ca12b5 (rebase: add concludememorynode(), and call it when rebasing in-memory, 2017-12-07).) Differential Revision: https://phab.mercurial-scm.org/D2760

rebase: fix issue 5494 also with --collapse Differential Revision: https://phab.mercurial-scm.org/D2759

rebase: also include commit of collapsed commits in single transaction When rebase.singletransaction is set, we still used to create a second transaction when committing with --collapse. It's simpler to create a single transaction. Note that in the affected .t file, the test that uses --collapse still appears to create two transactions (it prints "rebase status stored" twice). However, only a single transaction is actually created and the second printout comes from cmdutil.commitforceeditor() that explicitly calls tr.writepending(). Also note the that we now roll back any commits if the user closes the commit message editor with an error code (or leaves the message empty). That might be unfortunate, but it's consistent with how we behave in the --no-collapse case (if the user passed --edit). If we want to change that, I think it should be done consistently in a separate patch. Differential Revision: https://phab.mercurial-scm.org/D2728

lfs: debug print HTTP headers and JSON payload received from the server This has been extremely valuable to show divergences between `hg serve` and `lfs-test-server`. Once the `hg serve` code lands, there will be a certain amount of conditionalizing that needs to be done, because `lfs-test-server` doesn't always follow its spec. The $ISO_8601_DATE_TIME$ pattern masks the fact that `lfs-test-serve` is sending out an expires_at value of "0001-01-01T00:00:00Z". `hg serve` will (probably) use current time + 10 minutes or similar. The $HTTP_DATE$ is the current time.

test-lfs: dial up the debugging on commands that interact with the server This will be useful to let the client print out the HTTP headers and JSON in a future patch, so we can compare native LFS serving against test-lfs-server behavior. There tends to be a lot of debug stuff that we don't care about here in a push, so I was tempted to print this output with a [devel] config. But this will be useful for field debugging too, so just put up with the extra output here. It would have been nice to be able to set ui.debug once, but issue5815 prevents that.

tests: add a substitution pattern for dates in HTTP headers and LFS payload This will be useful when printing HTTP headers and JSON payload received from an LFS server. The RFC 1123 date masking has uses elsewhere too.