* y/go:
  go/zodb/zodbtools/dump: Don't use goto

Tomáš Peterka noticed that gotos in dump.go are not actually needed because
the same functionality could be achieved with defer in more clean and
structured way.

Do it.

This brings ~ 5% performance hit

	name        old time/op  new time/op  delta
	ZodbDump-4   148µs ± 1%   155µs ± 2%  +4.69%  (p=0.000 n=9+10)

because defer implementation is currently not great
(https://github.com/golang/go/issues/14939)

If we absolutely need those 5% back it could be worked around similar to
e.g. FileStorage.Load:

https://lab.nexedi.com/kirr/neo/blob/6faed528/go/zodb/storage/fs1/filestorage.go#L133
https://lab.nexedi.com/kirr/neo/blob/6faed528/go/zodb/storage/fs1/filestorage.go#L141

/suggested-by @katomaso

NEO 1.9

* tag 'v1.9':
  Release version 1.9
  master: fix resumption of backup replication (internal or not)
  master: fix/simplify generation of TID
  master: fix possible failure when reading data in a backup cluster with replicas

For both current backends (SQLite and fs1) there is currently a problem
of working with UTF-8 filenames if opening is handled via urls. For
example if backend string is

	sqlite://neo.sqlite·P1-1

after parsing as URL and further reassembled as string it will be

	neo.sqlite%C2%B7P1-1

with then errors like

	neo.sqlite%C2%B7P1-1: open: unable to open database file

showing.

Since storage backends primarily work with local files it makes sense
not to play raw url reassembly games and just pass raw strings to
backends for open.

SQLite uri processing is still possible, via e.g.

	sqlite://file:filepath?param=value,...

See

	https://www.sqlite.org/c3ref/open.html	and
	https://www.sqlite.org/uri.html

for details.

Previously when the code was trying to load testdata/ files with
different CWD it was failing with something like

	testdata/zlib/wczdata: no such file or directory.

Fix it by constructing testdata path relative to __file__ of
corresponding source.

When source device is mounted multiple times, findmnt reports it e.g.
this way:

	|-/mnt/SLAPOS                         /dev/md2     ext4       rw,relatime,stripe=256,data=ordered
	|-/srv/slapgrid                       /dev/md2[/srv/slapgrid]
	                                                   ext4       rw,relatime,stripe=256,data=ordered
	|-/opt/slapgrid                       /dev/md2[/opt/slapgrid]
	                                                   ext4       rw,relatime,stripe=256,data=ordered
	`-/opt/slapos                         /dev/md2[/opt/slapos]
	                                                   ext4       rw,relatime,stripe=256,data=ordered

and then it breaks:

	$ ./neotest info-local
	date:   Mon, 26 Mar 2018 21:52:08 +0200
	xnode:  slapuser5@sd-102959.dedibox.fr (2001:67c:1254:e:49::1 (+ 17·ipv6) 10.0.31.249 (+ 17·ipv4))
	uname:  Linux vifibcloud-onlinenet-hosting-002 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2+deb8u3 (2016-07-02) x86_64 GNU/Linux
	cpu:    Intel(R) Xeon(R) CPU D-1531 @ 2.20GHz
	cpu/[0-11]/freq: intel_pstate/powersave [0.80GHz - 2.70GHz]
	cpu/[0-11]/idle: acpi_idle/menu: POLL·0/0 C1·1/2 C2·41/82 # elat/tres µs
	WARNING: cpu: frequency not fixed - benchmark timings won't be stable
	WARNING: cpu: C-state exit-latency is max 41μs - benchmark timings won't be stable
	WARNING: cpu: (up to that might be adding to networked and IPC request-reply latency)
	realpath: '/dev/md2[/srv/slapgrid]': No such file or directory

Fix it by telling findmnt to not include '[/dir]' (-v option).

While we are here also add -u which means "Do not truncate text in columns"
which is also good to have on a safe side.

In particular try to support ZEO4:

- during handshake we now first wait for remote server to announce its
  preferred protocol, and only then send the version we select to use.
  This is the procedure original ZEO server-client do.

- teach rpc.call to decode exceptions not only for how ZEO5 encodes them
  (marking via 2 flag in "async" field), but also on how ZEO4 and
  earlier encode them: via replying with (exc_type, exc_inst) and
  expecting client to dynamically check exc_type is a subtype of
  Exception.

- handle other protocol differences - e.g. ZEO5 returns last_tid on
  register(), while earlier versions return nothing there.