gnu: perl-compress-raw-zlib: Update to 2.074.

* gnu/packages/compression.scm (perl-compress-raw-zlib): Update to 2.074.

gnu: openssh: Update to 7.5p1.

* gnu/packages/ssh.scm (openssh): Update to 7.5p1.

gnu: ntp: Update to 4.2.8p10 [security fixes].

Fixes CVE-2016-9042 and CVE-2017-{6451,6452,6455,6458,6459,6460,6462,6463,6464}
and others. See 'NEWS' in the source code for more information.

* gnu/packages/ntp.scm (ntp): Update to 4.2.8p10.

gnu: python-psycopg2: Update to 2.6.2.

* gnu/packages/python.scm (python-psycopg2): Update to 2.6.2.

gnu: python-zope-component: Update to 4.3.0.

* gnu/packages/python.scm (python-zope-component): Update to 4.3.0.
[source]: Use pypi-uri.

gnu: python-atomicwrites: Update to 1.1.5.

* gnu/packages/python.scm (python-atomicwrites): Update to 1.1.5.

gnu: python-texttable: Update to 0.8.7.

* gnu/packages/python.scm (python-texttable): Update to 0.8.7.

gnu: python-feedgenerator: Update to 1.9.

* gnu/packages/python.scm (python-feedgenerator): Update to 1.9.

gnu: python-wrapt: Update to 1.10.8.

* gnu/packages/python.scm (python-wrapt): Update to 1.10.8.
[source]: Use pypi-uri.

gnu: python-py: Update to 1.4.32.

* gnu/packages/python.scm (python-py): Update to 1.4.32.

gnu: python-sphinx-cloud-sptheme: Update to 1.8.0.

* gnu/packages/python.scm (python-sphinx-cloud-sptheme): Update to 1.8.0.

gnu: python-wcwidth: Update to 0.1.7.

* gnu/packages/python.scm (python-wcwidth): Update to 0.1.7.
[source]: Use pypi-uri.

gnu: python-markdown: Update to 2.6.8.

* gnu/packages/python.scm (python-markdown): Update to 2.6.8.

gnu: dns: Return #t instead of something undefined.

* gnu/packages/dns.scm (yadifa, knot)[arguments]: Return #t after calling
‘substitute*’.
(knot)[source]: Return #t after calling ‘delete-file-recursively’.

file-systems: Add missing docstring.

* gnu/system/file-systems.scm (file-system-type-predicate): Add
docstring.

file-systems: Do not use (gnu packages …).

Fixes a regression introduced in
7208995426714c9fc3ad59cadc3cc0f52df0f018 whereby (gnu system
file-systems) would pull in (gnu packages …) module, which in turn
breaks when importing things like (gnu build shepherd).

* gnu/system/file-systems.scm (file-system-type-predicate): Export.
(file-system-packages): Move to...
* gnu/system/linux-initrd.scm (file-system-packages): ... here.  Add
docstring.
* gnu/services/base.scm: Use it.
* tests/file-systems.scm ("does not pull (gnu packages …)"): New test.

gnu: vapoursynth: Update to 37.

* gnu/packages/video.scm (vapoursynth): Update to 37.

gnu: zimg: Update to 2.5.

* gnu/packages/image.scm (zimg): Update to 2.5.

tests: ssh: Add a test for SFTP.

* gnu/tests/ssh.scm (run-ssh-test): Introduce "SFTP file writing and reading".
Make 'sftp?' a keyword parameter.
(%test-openssh): Pass #:sftp? #t to 'run-ssh-test'.

tests: ssh: Abstract session connection and authentication.

* gnu/tests/ssh.scm (run-ssh-test): Introduce make-session-for-test,
call-with-connected-session and call-with-connected-session/auth.
(run-ssh-test)["connect"]: Rename to "shell command".  Abstract its session
connection and authentication work into the above three functions.