Provide branch information for both Emacs and Tramp (Bug#33328)

* doc/lispref/intro.texi (Version Info):
Document `emacs-repository-version' and `emacs-repository-branch'.

* etc/NEWS: Mention `emacs-repository-branch'.

* lisp/loadup.el: Initialize `emacs-repository-branch'.

* lisp/version.el (emacs-repository-branch): New variable.
(emacs-repository-branch-git, emacs-repository-get-branch):
New defuns.

* lisp/mail/emacsbug.el (report-emacs-bug):
Insert `emacs-repository-branch'.

* lisp/net/tramp.el (tramp-get-local-gid):
Use `group-name' if available.
(tramp-debug-message):
* lisp/net/tramp-cmds.el (tramp-bug): Report also
`tramp-repository-branch' and `tramp-repository-version'.

* lisp/net/trampver.el (tramp-repository-branch)
(tramp-repository-version): New defconst.
(tramp-repository-get-version): Remove.

3 files changed, 27 insertions, 17 deletions

diff --git a/lisp/net/tramp-cmds.el b/lisp/net/tramp-cmds.el
index 456300e7662..3c8f182ae97 100644
--- a/lisp/net/tramp-cmds.el
+++ b/lisp/net/tramp-cmds.el
@@ -198,8 +198,9 @@ This includes password cache, file cache, connection cache, buffers."
 	  ;; In rare cases, it could contain the password.  So we make it nil.
 	  tramp-password-save-function)
       (reporter-submit-bug-report
-       tramp-bug-report-address		; to-address
-       (format "tramp (%s)" tramp-version) ; package name and version
+       tramp-bug-report-address	  ; to-address
+       (format "tramp (%s %s/%s)" ; package name and version
+	       tramp-version tramp-repository-branch tramp-repository-version)
        (sort
 	(delq nil (mapcar
 	  (lambda (x)
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 44d66404f15..e8d535e85ed 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -1609,10 +1609,13 @@ ARGUMENTS to actually emit the message (if applicable)."
 	";; Emacs: %s Tramp: %s -*- mode: outline; -*-"
 	emacs-version tramp-version))
       (when (>= tramp-verbose 10)
-	(insert
-	 (format
-	  "\n;; Location: %s Git: %s"
-	  (locate-library "tramp") (tramp-repository-get-version)))))
+	(let ((tramp-verbose 0))
+	  (insert
+	   (format
+	    "\n;; Location: %s Git: %s/%s"
+	    (locate-library "tramp")
+	    (or tramp-repository-branch "")
+	    (or tramp-repository-version ""))))))
     (unless (bolp)
       (insert "\n"))
     ;; Timestamp.
diff --git a/lisp/net/trampver.el b/lisp/net/trampver.el
index de76788cc0e..f93e5380849 100644
--- a/lisp/net/trampver.el
+++ b/lisp/net/trampver.el
@@ -38,17 +38,23 @@
 (defconst tramp-bug-report-address "tramp-devel@gnu.org"
   "Email address to send bug reports to.")
 
-(defun tramp-repository-get-version ()
-  "Try to return as a string the repository revision of the Tramp sources."
-  (let ((dir (locate-dominating-file (locate-library "tramp") ".git")))
-    (when dir
-      (with-temp-buffer
-	(let ((default-directory (file-name-as-directory dir)))
-	  (and (zerop
-		(ignore-errors
-		  (call-process "git" nil '(t nil) nil "rev-parse" "HEAD")))
-	       (not (zerop (buffer-size)))
-	       (replace-regexp-in-string "\n" "" (buffer-string))))))))
+(defconst tramp-repository-branch
+  (ignore-errors
+    ;; Suppress message from `emacs-repository-get-branch'.
+    (let ((inhibit-message t))
+      ;; `emacs-repository-get-branch' has been introduced with Emacs 27.1.
+      (with-no-warnings
+	(emacs-repository-get-branch
+	 (locate-dominating-file (locate-library "tramp") ".git")))))
+  "The repository branch of the Tramp sources.")
+
+(defconst tramp-repository-version
+  (ignore-errors
+    ;; Suppress message from `emacs-repository-get-version'.
+    (let ((inhibit-message t))
+      (emacs-repository-get-version
+       (locate-dominating-file (locate-library "tramp") ".git"))))
+  "The repository revision of the Tramp sources.")
 
 ;; Check for Emacs version.
 (let ((x   (if (not (string-lessp emacs-version "24.1"))