test-subrepo-recursion.t: fix progress output on no-hardlink systems

test-ssh: stablize for platform-specific shell quoting Windows and OpenVMS use double quotes instead of single.

push: catch and process PushkeyFailed error We add a way to register "pushkey failure callback" that will be used if the push is aborted by a pushkey failure. A part generator adding mandatory pushkey parts should register a failure callback for all of them. The callback will be in charge of generating a meaningful abort if this part fails. If no callback is registered, the error is propagated. Catch PushkeyFailed error in exchange.

bundle2: introduce a PushkeyFail error to abort unbundle on pushkey error The pushkey code is generic and the server side has little context on what the client is trying to achieve. Generating interesting error messages server side would be challenging. Instead we introduce a dedicated exception that carries more data. In particular, it carries the id of the part which failed that will allow clients to display custom error messages depending on the part intent. The processing and transfer-over-the-wire of this exception is to be implemented in coming changesets.

record: exiting editor with non-zero status should not stop recording session Before this patch, exiting a hunk edit in record with a non-zero status lead to the end of the recording session, losing previously-selected hunks to record. This patch introduces the more desirable behavior of warning the user and continuing the recording session.

progress: stop double-wrapping of ui class We were wrapping the ui class again and again (uisetup, reposetup, subrepo setup, remote repo setup, etc). We now avoid that. This has impact on tests that were double-printing data because of this.

bundle2: abort when a mandatory pushkey part fails So far, result of a pushkey operation had no consequence on the transaction (beside the change). We makes it respect the 'mandatory' flag of part so that failed pushkey call abort the whole transaction. This will allow rejecting changes (primary target: changesets) regarding phases or bookmark criteria in the future (when we will push such data in a mandatory part). We currently raise an abort error because all clients support it. We'll introduce a more precise error in the next changesets.

push: make pushkey part advisory The current behavior (with bundle1) is to let the rest of the push succeed if the pushkey call (phases, bookmarks) failed (this comes from the fact that each item is sent in its own command). We kept this behavior with bundle2, which is highly debatable, but let us keep thing as they are now as a start. We are about to enforce 'mandatory' pushkey part as 'mandatory' successful, so we need to marks parts as advisory to preserve the current (debatable) behavior.

bundle2: pull bookmark the old way if no bundle2 listkeys support (issue4701) All known server implementations have listkeys support with bundle2, but people in the process of implementing new servers may not. Let's be nice with them.

tests: simplify printenv calls Make printenv executable so that we don't need python, TESTDIR, or quoting.