emacs: Fix refresh of search results to leave cursor on current thread.

This has been broken since the addition of support for streaming
search results to the emacs interface. With the old apparoach it was
easy to simply wait for all search results to land in the buffer and
then search for the desired line. With streaming results, we have to
save the target off to the side and allow the process filter and
sentinel functions to correctly respond when the target thread
appears.

notmuch.el

@@ -1246,6 +1246,8 @@ matching this search term are shown if non-nil. "
 (fset 'notmuch-search-mode-map notmuch-search-mode-map)
 
 (defvar notmuch-search-query-string)
+(defvar notmuch-search-target-thread)
+(defvar notmuch-search-target-position)
 (defvar notmuch-search-oldest-first t
   "Show the oldest mail first in the search-mode")
 
@@ -1346,6 +1348,8 @@ Complete list of currently available key bindings:
   (kill-all-local-variables)
   (make-local-variable 'notmuch-search-query-string)
   (make-local-variable 'notmuch-search-oldest-first)
+  (make-local-variable 'notmuch-search-target-thread)
+  (make-local-variable 'notmuch-search-target-position)
   (set (make-local-variable 'scroll-preserve-screen-position) t)
   (add-to-invisibility-spec 'notmuch-search)
   (use-local-map notmuch-search-mode-map)
@@ -1460,12 +1464,14 @@ This function advances the next thread when finished."
   "Add a message to let user know when \"notmuch search\" exits"
   (let ((buffer (process-buffer proc))
 	(status (process-status proc))
-	(exit-status (process-exit-status proc)))
+	(exit-status (process-exit-status proc))
+	(never-found-target-thread nil))
     (if (memq status '(exit signal))
 	(if (buffer-live-p buffer)
 	    (with-current-buffer buffer
 	      (save-excursion
-		(let ((inhibit-read-only t))
+		(let ((inhibit-read-only t)
+		      (atbob (bobp)))
 		  (goto-char (point-max))
 		  (if (eq status 'signal)
 		      (insert "Incomplete search results (search process was killed).\n"))
@@ -1474,11 +1480,17 @@ This function advances the next thread when finished."
 			(insert "End of search results.")
 			(if (not (= exit-status 0))
 			    (insert (format " (process returned %d)" exit-status)))
-			(insert "\n"))))))))))
+			(insert "\n")
+			(if (and atbob
+				 notmuch-search-target-thread)
+			    (set 'never-found-target-thread t))))))
+	      (if never-found-target-thread
+		  (goto-char notmuch-search-target-position)))))))
 
 (defun notmuch-search-process-filter (proc string)
   "Process and filter the output of \"notmuch search\""
-  (let ((buffer (process-buffer proc)))
+  (let ((buffer (process-buffer proc))
+	(found-target nil))
     (if (buffer-live-p buffer)
 	(with-current-buffer buffer
 	  (save-excursion
@@ -1501,9 +1513,16 @@ This function advances the next thread when finished."
 			(insert (format "%s %-7s %-40s %s (%s)\n" date count authors subject tags))
 			(put-text-property beg (point-marker) 'notmuch-search-thread-id thread-id)
 			(put-text-property beg (point-marker) 'notmuch-search-authors authors)
-			(put-text-property beg (point-marker) 'notmuch-search-subject subject))
+			(put-text-property beg (point-marker) 'notmuch-search-subject subject)
+			(if (and notmuch-search-target-thread
+				 (string= thread-id notmuch-search-target-thread))
+			    (progn
+			      (set 'found-target beg)
+			      (set 'notmuch-search-target-thread nil))))
 		      (set 'line (match-end 0)))
-		  (set 'more nil))))))
+		  (set 'more nil)))))
+	  (if found-target
+	      (goto-char found-target)))
       (delete-process proc))))
 
 (defun notmuch-search-operate-all (action)
@@ -1530,14 +1549,27 @@ characters as well as `_.+-'.
 	   (append action-split (list notmuch-search-query-string) nil))))
 
 ;;;###autoload
-(defun notmuch-search (query &optional oldest-first)
-  "Run \"notmuch search\" with the given query string and display results."
+(defun notmuch-search (query &optional oldest-first target-thread target-position)
+  "Run \"notmuch search\" with the given query string and display results.
+
+The optional parameters are used as follows:
+
+  oldest-first: A Boolean controlling the sort order of returned threads
+  target-thread: A thread ID (with the thread: prefix) that will be made
+                 current if it appears in the search results.
+  saved-position: If the search results complete, and the target thread is
+                  not found in the results, and the point is still at the
+                  beginning of the buffer, then the point will be moved to
+                  the saved position.
+"
   (interactive "sNotmuch search: ")
   (let ((buffer (get-buffer-create (concat "*notmuch-search-" query "*"))))
     (switch-to-buffer buffer)
     (notmuch-search-mode)
     (set 'notmuch-search-query-string query)
     (set 'notmuch-search-oldest-first oldest-first)
+    (set 'notmuch-search-target-thread target-thread)
+    (set 'notmuch-search-target-position target-position)
     (let ((proc (get-buffer-process (current-buffer)))
 	  (inhibit-read-only t))
       (if proc
@@ -1568,11 +1600,9 @@ same relative position within the new buffer."
 	(thread (notmuch-search-find-thread-id))
 	(query notmuch-search-query-string))
     (kill-this-buffer)
-    (notmuch-search query oldest-first)
+    (notmuch-search query oldest-first thread here)
     (goto-char (point-min))
-    (if (re-search-forward (concat "^" thread) nil t)
-	(beginning-of-line)
-      (goto-char here))))
+    ))
 
 (defun notmuch-search-toggle-order ()
   "Toggle the current search order.