org-colview: Remove error upon summarizing non-numbers with a format string

* lisp/org-colview.el (org-columns--displayed-value): Remove check.
* testing/lisp/test-org-colview.el (test-org-colview/columns-summary):
  Remove a test.

Reported-by: Hendrik Tews <hendrik@askra.de>
<http://permalink.gmane.org/gmane.emacs.orgmode/113600>

lisp/org-colview.el

@@ -237,17 +237,9 @@ display, as a string."
 		 "* "
 		 (org-columns-compact-links value)))
 	(`(,_ ,_ ,_ ,_ nil) value)
-	;; If PRINTF is set, and we are displaying a number, obey to
-	;; it.  Otherwise, raise an error.
-	(`(,_ ,name ,_ ,_ ,printf)
-	 (when (or (not (string-match-p "[0-9]" value))
-		   (and (string-match-p "[1-9]" value)
-			(= 0 (string-to-number value))))
-	   (user-error "Invalid value: %S.  \
-Format string in operator implies column %S only contains numbers"
-		       value
-		       name))
-	 (format printf (string-to-number value)))
+	;; If PRINTF is set, assume we are displaying a number and
+	;; obey to the format string.
+	(`(,_ ,name ,_ ,_ ,printf) (format printf (string-to-number value)))
 	(_ (error "Invalid column specification format: %S" spec)))))
 
 (defun org-columns--collect-values (&optional compiled-fmt)

testing/lisp/test-org-colview.el

@@ -223,16 +223,6 @@
 :END:"
       (let ((org-columns-default-format "%A{+;%.1f}")) (org-columns))
       (get-char-property (point) 'org-columns-value-modified))))
-  ;; Raise an error when format strings are applied to non-numbers.
-  (should-error
-   (org-test-with-temp-text
-       "* H
-** S1
-:PROPERTIES:
-:A: foo
-:END:"
-     (let ((org-columns-default-format "%A{+;%.2f}")) (org-columns))
-     (get-char-property (point) 'org-columns-value-modified)))
   ;; {:} sums times.  Plain numbers are hours.
   (should
    (equal