bundle2: convey PushkeyFailed error over the wire
We add a way to convey the precise exception. This will allow better error
message on the server.
bundle2: also capture reply capability on failure
When unbundling over the wire is aborted, we have a mechanism to convey the
error inside a bundle part. As we add support for more errors, we need to know if
the client will support them. For this purpose, we duck punch the reply
capabilities of the client on the raised extensions.
This is similar to what is done to salvage the server output on error.
bundle2: add an 'error' capability
This capability will be extended as new error type is introduced.
hgewb: disable progress when serving (
issue4582)
Before this patch, progress bar could be displayed when serving, creating
hypothetical problems.
test-ssh: stablize for platform-specific shell quoting
Windows and OpenVMS use double quotes instead of single.