Steps to reproduce the issue

Install new Joomla 3.4.8
Configure in Joomla Update Component the Update Channel to Testing
Perform update to 3.5 RC4.

Expected result

All be fine. No errors on Extensions > Manage > Database .

Actual result

message " 0 ERROR: syntax error at or near ""#__contentitem_tag_map_idx_tag"" LINE 1: ...LTER TABLE "#__contentitem_tag_map" DROP INDEX "#__con... ^SQL=ALTER TABLE "#__contentitem_tag_map" DROP INDEX "#__contentitem_tag_map_idx_tag";"

When going to Extensions > Manage > Database following is shown:

Warning: Database is not up to date!
3 Database Problems Found.
Other Information

Database schema version (3.4.4-2015-07-11) does not match CMS version (3.5.0-2016-03-01).
Table 'bsxro_redirect_links' does not have column 'new_url' with type varchar. (From file 3.5.0-2016-03-01.sql.)
Table 'bsxro_redirect_links' does not have column 'referer' with type varchar. (From file 3.5.0-2016-03-01.sql.)

System information (as much as possible)

See attachment; unfortunately systeminfo is not allowed as attachment.

PHP Built On Linux scotchbox 3.13.0-55-generic #94-Ubuntu SMP Thu Jun 18 00:27:10 UTC 2015 x86_64
Database Version 9.3.10
Database Collation en_US.UTF-8
Database Connection Collation UTF8
PHP Version 5.6.14-1+deb.sury.org~trusty+1
Web Server Apache/2.4.16 (Ubuntu)
WebServer to PHP Interface apache2handler
Joomla! Version Joomla! 3.5.0-rc4 Release Candidate [ Ember ] 16-March-2016 00:45 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.87 Safari/537.36

Additional comments

I have reproduced this with the same configuration. With MySQL no problems found on same procedure.