Propagate remote process environment.

* net/tramp-sh.el (tramp-sh-handle-start-file-process)
(tramp-sh-handle-process-file): Propagate `process-environment'.

* vc/vc-hg.el (vc-hg-state): No special handling for remote files;
Tramp propagates environment variables now.
Merge branch 'master' of git.sv.gnu.org:/srv/git/emacs
newsticker: Fix bug#18787: Tell libxml-parse-xml-region to discard comments.

* lisp/net/newst-backend.el (newsticker--sentinel-work): Tell
`libxml-parse-xml-region' to discard comments. Fixes bug#18787.