I've noticed that this problem does no longer occur if bash 4.2.8 is configured --with-bash-malloc. On my distribution (arch) bash is configured --without-bash-malloc by default.
This is the configuration i use now (derived from the archlinux
pkgbuild):
./configure --prefix=/usr --with-curses --enable-readline \
--with-bash-malloc --with-installed-readline \
--bindir=/bin --mandir=/usr/share/man --infodir=/usr/share/info
