Fix property name completion

* lisp/org-pcomplete.el (pcomplete/org-mode/prop): Add
  `ignore-malformed' argument in call to `org-buffer-property-keys'

* lisp/org.el (org-buffer-property-keys): Add support for new argument
  `ignore-malformed'.

* testing/lisp/test-org-pcomplete.el: Add new file for testing
  `pcomplete' integration.

* testing/lisp/test-org.el (test-org/buffer-property-keys): Test
  behaviour of `org-buffer-property-keys' with new `ignore-malformed'
  argument.

When property name completion is being performed, it means that we are
inside malformed property drawer that will become valid only after
successful completion. In this case in makes no sense to perform
interactive drawer repair.

lisp/org-pcomplete.el

@@ -359,7 +359,7 @@ This needs more work, to handle headings with lots of spaces in them."
 	     (concat x ": "))
 	   (let ((lst (pcomplete-uniqify-list
 		       (copy-sequence
-			(org-buffer-property-keys nil t t)))))
+			(org-buffer-property-keys nil t t t)))))
 	     (dolist (prop (org-entry-properties))
 	       (setq lst (delete (car prop) lst)))
 	     lst))

lisp/org.el

@@ -16121,7 +16121,8 @@ decreases scheduled or deadline date by one day."
 	  (org-indent-line)))))
     (run-hook-with-args 'org-property-changed-functions property value)))
 
-(defun org-buffer-property-keys (&optional specials defaults columns)
+(defun org-buffer-property-keys
+    (&optional specials defaults columns ignore-malformed)
   "Get all property keys in the current buffer.
 
 When SPECIALS is non-nil, also list the special properties that
@@ -16132,7 +16133,10 @@ special meaning internally: ARCHIVE, CATEGORY, SUMMARY,
 DESCRIPTION, LOCATION, and LOGGING and others.
 
 When COLUMNS in non-nil, also include property names given in
-COLUMN formats in the current buffer."
+COLUMN formats in the current buffer.
+
+When IGNORE-MALFORMED is non-nil, malformed drawer repair will not be
+automatically performed, such drawers will be silently ignored."
   (let ((case-fold-search t)
 	(props (append
 		(and specials org-special-properties)
@@ -16144,7 +16148,8 @@ COLUMN formats in the current buffer."
        (let ((range (org-get-property-block)))
 	 (catch 'skip
 	   (unless range
-	     (when (and (not (org-before-first-heading-p))
+	     (when (and (not ignore-malformed)
+			(not (org-before-first-heading-p))
 			(y-or-n-p (format "Malformed drawer at %d, repair?"
 					  (line-beginning-position))))
 	       (org-get-property-block nil t))

testing/lisp/test-org-pcomplete.el

@@ -0,0 +1,43 @@
+;;; test-org-pcomplete.el --- test pcomplete integration
+
+;; Copyright (C) 2015  Alexey Lebedeff
+;; Authors: Alexey Lebedeff
+
+;; This file is not part of GNU Emacs.
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Comments:
+
+
+
+;;; Code:
+
+(ert-deftest test-org-pcomplete/prop ()
+  "Test property completion behaviour in an Org buffer"
+  ;; Drawer where we are currently completing property name is
+  ;; malformed in any case, it'll become valid only after successful
+  ;; completion.  We expect that this completion process will finish
+  ;; successfully, and there will be no interactive drawer repair
+  ;; attempts.
+  (should
+   (equal
+    "* a\n:PROPERTIES:\n:pname: \n:END:\n* b\n:PROPERTIES:\n:pname: pvalue\n:END:\n"
+    (org-test-with-temp-text "* a\n:PROPERTIES:\n:pna<point>\n:END:\n* b\n:PROPERTIES:\n:pname: pvalue\n:END:\n"
+      (flet ((y-or-n-p (prompt) (error "Should not be called")))
+	(pcomplete))
+      (buffer-string)))))
+
+(provide 'test-org-pcomplete)
+;;; test-org-pcomplete.el ends here

testing/lisp/test-org.el

@@ -3352,7 +3352,13 @@ Paragraph<point>"
    (equal '("A" "B" "COLUMNS")
 	  (org-test-with-temp-text
 	      "* H\n:PROPERTIES:\n:COLUMNS: %25ITEM %A %20B\n:END:"
-	    (org-buffer-property-keys nil nil t)))))
+	    (org-buffer-property-keys nil nil t))))
+  ;; With non-nil IGNORE-MALFORMED malformed property drawers are silently ignored.
+  (should
+   (equal '("A")
+	  (org-test-with-temp-text
+	      "* a\n:PROPERTIES:\n:A: 1\n:END:\n* b\n:PROPERTIES:\nsome junk here\n:END:\n"
+	    (org-buffer-property-keys nil nil nil t)))))
 
 (ert-deftest test-org/property-values ()
   "Test `org-property-values' specifications."