I have just upgraded successfully centos6 64bit from 7.2.0 to 8.0.0, only issue (but I dunno if it's an issue):

Code:
ERROR 1133 (42000) at line 2: Can't find any matching row in the user table
ERROR 1396 (HY000) at line 1: Operation DROP USER failed for ''@'zimbra.idc3.xxxxx.net'
this is the detail:
Code:
Restoring existing configuration file from /opt/zimbra/.saveconfig/localconfig.xml...done
Operations logged to /tmp/zmsetup.09222012-182506.log
Upgrading from 7.2.0_GA_2669 to 8.0.0_GA_5434
Stopping zimbra services...done.
Starting mysql...done.
This appears to be 7.2.0_GA
Upgrading ldap data...done.
Upgrading LDAP configuration database...done.
Loading database...done.
Checking ldap status...not running.
Running zmldapapplyldif...done.
Checking ldap status...not running.
Starting ldap...done.
Checking ldap status...already running.
Redolog version update required.
Sat Sep 22 18:25:58 2012: Verified redolog version 1.31.
Sat Sep 22 18:25:58 2012: Updating Redolog schema version from 1.31 to 1.42.
Redolog version update finished.
Schema upgrade required from version 65 to 91.
Running /opt/zimbra/libexec/scripts/migrate20120611_7to8_bundle.pl
Sat Sep 22 18:26:00 2012: Verified schema version 65.
Sat Sep 22 18:26:01 2012: Adding device information columns to ZIMBRA.MOBILE_DEVICES table...
Sat Sep 22 18:26:02 2012: Adding ZIMBRA.PENDING_ACL_PUSH table...
Sat Sep 22 18:26:03 2012: Adding TAG table...
..........
Sat Sep 22 18:26:14 2012: Adding TAGGED_ITEM table...
..........
Sat Sep 22 18:26:25 2012: Adding version and last_purge_at columns to ZIMBRA.MAILBOX table...
Sat Sep 22 18:26:26 2012: Adding/Modifying columns in mail_item, mail_item_dumpster, revision, revision_dumpster tables...
..........
..........
..........
..........
Sat Sep 22 18:27:37 2012: Dropping IM tables...
Sat Sep 22 18:27:39 2012: Verified schema version 65.
Sat Sep 22 18:27:39 2012: Updating DB schema version from 65 to 90.
Running /opt/zimbra/libexec/scripts/migrate20120410-BlobLocator.pl
Sat Sep 22 18:27:41 2012: Verified schema version 90.
Sat Sep 22 18:29:24 2012: Verified schema version 90.
Sat Sep 22 18:29:24 2012: Updating DB schema version from 90 to 91.
Stopping mysql...done.
Updating from 7.2.1_GA
Updating from 8.0.0_BETA1
Adding dynamic group configuration
Stopping ldap...done.
Checking ldap status...not running.
Running zmldapapplyldif...done.
Checking ldap status...not running.
Starting ldap...done.
Stopping ldap...done.
Checking ldap status...not running.
Running zmldapapplyldif...done.
Checking ldap status...not running.
Starting ldap...done.
Updating from 8.0.0_BETA2
Starting mysql...done.
ERROR 1133 (42000) at line 2: Can't find any matching row in the user table
ERROR 1396 (HY000) at line 1: Operation DROP USER failed for ''@'zimbra.idc3.xxxxx.net'
Stopping mysql...done.

...snip....