Don't have ffap interpret ":/bin" as the current directory

* lisp/ffap.el (ffap-file-at-point): Don't interpret :/bin as the
current directory (bug#52441).

lisp/ffap.el

@@ -1449,10 +1449,13 @@ which may actually result in an URL rather than a filename."
 	       (ffap-file-exists-string (substring name 0 (match-beginning 0)))))
 	 ;; If it contains a colon, get rid of it (and return if exists)
 	 ((and (string-match path-separator name)
-	       (setq name (ffap-string-at-point 'nocolon))
-	       (> (length name) 0)
-	       (ffap-file-exists-string name)))
-	 ;; File does not exist, try the alist:
+	       (let ((this-name (ffap-string-at-point 'nocolon)))
+                 ;; But don't interpret the first part if ":/bin" as
+                 ;; the empty string.
+	         (when (> (length this-name) 0)
+                   (setq name this-name)
+	           (ffap-file-exists-string name)))))
+         ;; File does not exist, try the alist:
 	 ((let ((alist ffap-alist) tem try case-fold-search)
 	    (while (and alist (not try))
 	      (setq tem (car alist) alist (cdr alist))

test/lisp/ffap-tests.el

@@ -141,6 +141,21 @@ left alone when opening a URL in an external browser."
         (let (kill-buffer-query-functions)
           (kill-buffer (call-interactively #'find-file-at-point)))))))
 
+(ert-deftest ffap-test-path ()
+  (with-temp-buffer
+    (insert "/usr/bin:/bin")
+    (goto-char (point-min))
+    (should (equal (ffap-file-at-point) "/usr/bin")))
+  (with-temp-buffer
+    (insert "/usr/bin:/bin")
+    (goto-char (point-min))
+    (search-forward ":")
+    (should (equal (ffap-file-at-point) "/bin")))
+  (with-temp-buffer
+    (insert ":/bin")
+    (goto-char (point-min))
+    (should (equal (ffap-file-at-point) nil))))
+
 (provide 'ffap-tests)
 
 ;;; ffap-tests.el ends here