QNetworkAccessManager crashes with glibc memory corruption

QNetworkAccessManager crashes frequently with glibc memory corruption or a SIGSEGV in 4.8.0-rc1 on Linux.

• • • glibc detected *** ./bearercrash: malloc(): memory corruption (fast)

Run the attached sample code a few times and it will crash after a few dozen runs. The code accesses a local URL http://localhost:3000/robots.txt which you may need to change.

The attached crashlog.txt is the console output when it crashes.
The attached gdbbacktrace.txt is the gdb backtrace of all threads from the core file.