Remove the build number from emacs-version variable

It's a largely internal detail that can confuse users.  (Bug#25590)
* lisp/version.el (emacs-build-number): New constant.
(emacs-version): Use emacs-build-number.
* lisp/loadup.el (top-level): When dumping, increment
emacs-build-number rather than emacs-version.
* src/emacs.c (emacs-version): Doc fix.
* doc/lispref/intro.texi (Version Info): Update emacs-version details.
Mention emacs-build-number.
* lisp/gnus/gnus-util.el (gnus-emacs-version):
* lisp/mail/emacsbug.el (report-emacs-bug):
* admin/admin.el (set-version): Update for emacs-version change.
; * etc/NEWS: Mention this.

4 files changed, 15 insertions, 12 deletions

diff --git a/lisp/gnus/gnus-util.el b/lisp/gnus/gnus-util.el
index ff5c2950914..20eceb58edd 100644
--- a/lisp/gnus/gnus-util.el
+++ b/lisp/gnus/gnus-util.el
@@ -1618,7 +1618,7 @@ sequence, this is like `mapcar'.  With several, it is like the Common Lisp
      ((not (memq 'emacs lst))
       nil)
      ((string-match "^\\(\\([.0-9]+\\)*\\)\\.[0-9]+$" emacs-version)
-      (concat "Emacs/" (match-string 1 emacs-version)
+      (concat "Emacs/" emacs-version
 	      (if system-v
 		  (concat " (" system-v ")")
 		"")))
diff --git a/lisp/loadup.el b/lisp/loadup.el
index ecb72840c43..5b19b05a82e 100644
--- a/lisp/loadup.el
+++ b/lisp/loadup.el
@@ -350,7 +350,7 @@ lost after dumping")))
 	 (multibyte-string-p default-directory))
     (error "default-directory must be unibyte when dumping Emacs!"))
 
-;; Determine which last version number to use
+;; Determine which build number to use
 ;; based on the executables that now exist.
 (if (and (equal (last command-line-args) '("dump"))
 	 (not (eq system-type 'ms-dos)))
@@ -364,10 +364,9 @@ lost after dumping")))
 			     files)))
       (setq emacs-repository-version (condition-case nil (emacs-repository-get-version)
                               (error nil)))
-      ;; `emacs-version' is a constant, so we shouldn't change it with `setq'.
-      (defconst emacs-version
-	(format "%s.%d"
-		emacs-version (if versions (1+ (apply 'max versions)) 1)))))
+      ;; A constant, so we shouldn't change it with `setq'.
+      (defconst emacs-build-number
+	(if versions (1+ (apply 'max versions)) 1))))
 
 
 (message "Finding pointers to doc strings...")
@@ -463,7 +462,7 @@ lost after dumping")))
                    ;; Don't bother adding another name if we're just
                    ;; building bootstrap-emacs.
                    (equal (last command-line-args) '("bootstrap"))))
-	  (let ((name (concat "emacs-" emacs-version))
+	  (let ((name (format "emacs-%s.%d" emacs-version emacs-build-number))
 		(exe (if (eq system-type 'windows-nt) ".exe" "")))
 	    (while (string-match "[^-+_.a-zA-Z0-9]+" name)
 	      (setq name (concat (downcase (substring name 0 (match-beginning 0)))
diff --git a/lisp/mail/emacsbug.el b/lisp/mail/emacsbug.el
index c8214c35108..ecb7db60ae1 100644
--- a/lisp/mail/emacsbug.el
+++ b/lisp/mail/emacsbug.el
@@ -151,10 +151,7 @@ Prompts for bug subject.  Leaves you in a mail buffer."
   (interactive "sBug Subject: ")
   ;; The syntax `version;' is preferred to `[version]' because the
   ;; latter could be mistakenly stripped by mailing software.
-  (if (eq system-type 'ms-dos)
-      (setq topic (concat emacs-version "; " topic))
-    (when (string-match "^\\(\\([.0-9]+\\)*\\)\\.[0-9]+$" emacs-version)
-      (setq topic (concat (match-string 1 emacs-version) "; " topic))))
+  (setq topic (concat emacs-version "; " topic))
   (let ((from-buffer (current-buffer))
 	(can-insert-mail (or (report-emacs-bug-can-use-xdg-email)
 			     (report-emacs-bug-can-use-osx-open)))
diff --git a/lisp/version.el b/lisp/version.el
index 99ab3519a7e..ea6f1b46948 100644
--- a/lisp/version.el
+++ b/lisp/version.el
@@ -44,6 +44,12 @@ This variable first existed in version 19.23.")
 (defconst emacs-build-time (if emacs-build-system (current-time))
   "Time at which Emacs was dumped out, or nil if not available.")
 
+(defconst emacs-build-number 1          ; loadup.el may increment this
+  "The build number of this version of Emacs.
+This is an integer that increments each time Emacs is built in a given
+directory (without cleaning).  This is likely to only be relevant when
+developing Emacs.")
+
 (defvar motif-version-string)
 (defvar gtk-version-string)
 (defvar ns-version-string)
@@ -56,8 +62,9 @@ Don't use this function in programs to choose actions according
 to the system configuration; look at `system-configuration' instead."
   (interactive "P")
   (let ((version-string
-         (format "GNU Emacs %s (%s%s%s%s)%s"
+         (format "GNU Emacs %s (build %s, %s%s%s%s)%s"
                  emacs-version
+                 emacs-build-number
 		 system-configuration
 		 (cond ((featurep 'motif)
 			(concat ", " (substring motif-version-string 4)))