Patch to remove excessive fcntl() calls was never ported correctly to 5.1
has always been a no-op in PS 5.1.
The reason is that the patch works by preprocessor, adding "... && !defined(NO_ALARM) " several times to net_serv.cc to disable the alarm code. But nothing in PS build process or official binary build scripts actually define NO_ALARM, it never gets defined, the alarm code never gets disabled.
Not a bug on PS 5.5, as CMake build sys starts defining NO_ALARM for us.