Merge from origin/emacs-25

Merge from origin/emacs-25

0377fe2 ; Spelling fixes
f253695 Update docs for `customize-mode'
4395aaa Fix documentation of 'assoc-string' and 'compare-strings'
ab0ebb9 ; Only load .elc file in tests.
a98aa02 Error on multibyte characters in HTTP request
ea512a7 * lisp/gnus/mm-decode.el (mm-convert-shr-links): Mask keys th...
8297331 ; Revert "Ensure undo-boundary after insert-file-contents."
dc5e65b Unset GIT_DIR when calling Git commands
6cdd8f7 Ensure undo-boundary after insert-file-contents.
4793f5f Clarify documentation of 'line-spacing' and 'line-height'
5f37572 Fix removal of variables from process-environment
e5e886d * admin/authors.el (authors-ignored-files, authors-valid-file...
db0777b * admin/authors.el (authors-aliases, authors-fixed-case): Add...

# Conflicts:
#	doc/lispref/modes.texi
#	lisp/gnus/mm-decode.el