I believe this bug was fixed with this version of the package (in Debian).  This was fixed in Precise, QUantal, and Raring at the very least.

php5 (5.3.6-11) unstable; urgency=low

  * Use more reasonable default number of processes for PHP5-FPM
  * Enable firebird support everywhere also in debian/rules
  * Don't delete still used session files (Closes: #626640)
  * Enable building of php5-interbase by adding Architecture: any
    to debian/control
  * Use dh_prep instead of dh_clean -k

 -- Ondrej Surý <ondrej@debian.org>  Sat, 14 May 2011 22:15:32 +0200