Merge from origin/emacs-25
b73f466 * lisp/cus-start.el (exec-path): Handle nil elements. (Bug#2...
55ebb70 Catch the imenu-unavailable error in sh-mode completion table
993acb5 ; Minor fix for last change in characters.el
30c4bb5 More char-width fixes
4eb4463 Fix char-width-table values for some Emoji
528997d Keep point when switching from and to *terminal* buffer
2130005 * INSTALL: Use correct Emacs release number 25.
10835b1 Avoid crashes due to objects read with the #n=object form
4de671d Improve doc string of 'completion-at-point-functions'
ceb46f0 Fix crash in evaluating functions
d8374c4 * src/filelock.c (current_lock_owner): Update comment.