Drush updates core successfully to 7.32 but is still 7.31

Question

I'm developing a site on Drupal 7 and using drush 7.0-dev to keep the core and modules up to date. I've run drush pm-update several times successfully in the past, until Drupal core version 7.32 came out. Everything seems to go fine and drush reports no errors, but the version still stays at 7.31 after the update.

Here's the output of two consecutive runs:

me@mybox:/var/www/customer$ drush pm-update
 Name    Installed Version  Proposed version  Message
 Drupal  7.31               7.32              SECURITY UPDATE available


Update information last refreshed: Thu, 10/23/2014 - 20:21
Code updates will be made to drupal core.
WARNING:  Updating core will discard any modifications made to Drupal core files, most noteworthy among these are .htaccess and robots.txt.  If you have made any modifications 
to these files, please back them up before updating so that you can re-create your modifications in the updated version of the file.
Note: Updating core can potentially break your site. It is NOT recommended to update production sites without prior testing.

Do you really want to continue? (y/n): y
Project drupal was updated successfully. Installed version is now 7.32.
Backups were saved into the directory /home/me/drush-backups/customer/20141023172524/drupal.                                                                                           [ok]
No database updates required                                                                                                                                                           [success]
'all' cache was cleared.                                                                                                                                                               [success]
Finished performing updates.                                                                                                                                                           [ok]
me@mybox:/var/www/customer$ drush pm-update
 Name    Installed Version  Proposed version  Message
 Drupal  7.31               7.32              SECURITY UPDATE available


Update information last refreshed: Thu, 10/23/2014 - 20:25
Code updates will be made to drupal core.
WARNING:  Updating core will discard any modifications made to Drupal core files, most noteworthy among these are .htaccess and robots.txt.  If you have made any modifications 
to these files, please back them up before updating so that you can re-create your modifications in the updated version of the file.
Note: Updating core can potentially break your site. It is NOT recommended to update production sites without prior testing.

Do you really want to continue? (y/n):

Am I doing something wrong? Why is the core not updating? Where should I start troubleshooting? I haven't tried a manual update yet, because I'd really rather get drush working again. The server is running Debian 7 and PHP 5.4.

Answer 1

Try drush up drupal. That may do the trick.

Answer 2

I finally figured it out - it was a permission problem. I hadn't noticed some of the directories drush was trying to update belonged to another user. Drush had no write permissions there but reported no errors. A quick chown later the update completed just fine.

Answer 3

I have been having a similar issue updating from 7.27 to 7.45 and I found that by changing my /etc/apache2/site-available adn editing my 000-default.conf file DocumentRoot /var/www

Mine were directing to the /var/www/html originally. Drupal now recognises the updates which I did using Drush but I now have an AJAX HTTP error... Please excuse any ignorance as I am new to Drupal and IT. I hope this helps others who like me found changing permissions does not solve the issue.