[support] Big problem with Drual 7.12 drush up

[Roger]

Hi all.
  I fresh installed Fedora 16 on a hd  here at home. There is no drush 
for Fedora 16 so followed the instructions for manual install Drupal 
7.21 install.
Worked ok. Dev and test are working.

I drush up 'd up my Ubuntu  drupal 7.10 dev and test installs and all 
worked well. Nothing had changed, both now 7.12 core.

I went to our server which is virtually identical to my ubuntu installs 
and via ssh drush up the development site then the live site and    -- 
all hell broke loose.
Both sites wrecked.
I get a server error for both.

With cpanel I uploaded a small index.html to each so it appears in the 
drupal install above the index.php in the file list and called that with 
www.site.com/index.html.
The page displays so there server is working.
So I copied the drupal-7.10.tar.gz  file to both and unzipped, copied 
the sites folder from the previously working sites to the 710 installs 
and it sort of works, -- theme is crapo but it worked.

It seems that drush failed to do the update correctly. This is worrying 
as we rely on drush and it has not failed before this.

Will it be ok if I copy the drupal-7.12.tar.gz to the server. Extract 
that and copy the original working /sites folder to the new install?
Are there any gotchas in this method.

Would it be better to rename the sites folder, delete the drupal 
install, copy the drupal 7.12 extraction files minus the /sites folder 
over to the working directory,  rename the xxsites folder to /sites so 
the install picks it all up.
Are there any gotchas in this method? Would it be better to go thru the 
install procedure and point it to the working database.

I caught a glimpse of a post that said to avoid 7.12 and revert to 7.11 
but there is no 7.11 only 7.10 so I felt this post to be inaccurate.

Does anyone have info on how to fix this problem please.
Thanks
Roger