It's permission problem. It is not "classic" read/write permissions of apache user, but selinux one.
Apache cannot write to files labeled as httpd_sys_content_t
they can be only read by apache.
You have 2 possibilities:
label svn repository files as httpd_sys_content_rw_t
:
chcon -R -t httpd_sys_content_rw_t /path/to/your/svn/repo
set selinux boolean httpd_unified --> on
setsebool -P httpd_unified=1
I prefer 2nd possibility. You can play also with other selinux booleans connected with httpd
:
getsebool -a | grep httpd