master f212daf: Fix recently introduced error in `tramp-sh-handle-vc-registered'

[Michael Albinus]

branch: master
commit f212daf0a96999b8c1e63217c22a86d6e1671687
Author: Michael Albinus <address@hidden>
Commit: Michael Albinus <address@hidden>

    Fix recently introduced error in `tramp-sh-handle-vc-registered'
    
    * lisp/net/tramp-sh.el (tramp-sh-handle-vc-registered): Improve test for
    `vc-handled-backends'.  (Bug#40670)
---
 lisp/net/tramp-sh.el | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index 95425cb..a39d503 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -3577,33 +3577,30 @@ STDERR can also be a file name."
            ;; calls shall be answered from the file cache.  We unset
            ;; `process-file-side-effects' and `remote-file-name-inhibit-cache'
            ;; in order to keep the cache.
-           (let ((vc-handled-backends vc-handled-backends)
+           (let ((vc-handled-backends (copy-sequence vc-handled-backends))
                  remote-file-name-inhibit-cache process-file-side-effects)
              ;; Reduce `vc-handled-backends' in order to minimize
              ;; process calls.
              (when (and
                     (memq 'Bzr vc-handled-backends)
-                    (not (and
-                          (bound-and-true-p vc-bzr-program)
-                          (with-tramp-connection-property v vc-bzr-program
-                            (tramp-find-executable
-                             v vc-bzr-program (tramp-get-remote-path v))))))
+                    (or (not (require 'vc-bzr nil 'noerror))
+                        (not (with-tramp-connection-property v vc-bzr-program
+                               (tramp-find-executable
+                                v vc-bzr-program (tramp-get-remote-path v))))))
                (setq vc-handled-backends (remq 'Bzr vc-handled-backends)))
              (when (and
                     (memq 'Git vc-handled-backends)
-                    (not (and
-                          (bound-and-true-p vc-git-program)
-                          (with-tramp-connection-property v vc-git-program
-                            (tramp-find-executable
-                             v vc-git-program (tramp-get-remote-path v))))))
+                    (or (not (require 'vc-git nil 'noerror))
+                        (not (with-tramp-connection-property v vc-git-program
+                               (tramp-find-executable
+                                v vc-git-program (tramp-get-remote-path v))))))
                (setq vc-handled-backends (remq 'Git vc-handled-backends)))
              (when (and
                     (memq 'Hg vc-handled-backends)
-                    (not (and
-                          (bound-and-true-p vc-hg-program)
-                          (with-tramp-connection-property v vc-hg-program
-                            (tramp-find-executable
-                             v vc-hg-program (tramp-get-remote-path v))))))
+                    (or (not (require 'vc-hg nil 'noerror))
+                        (not (with-tramp-connection-property v vc-hg-program
+                               (tramp-find-executable
+                                v vc-hg-program (tramp-get-remote-path v))))))
                (setq vc-handled-backends (remq 'Hg vc-handled-backends)))
              ;; Run.
              (tramp-with-demoted-errors