Custom variable class segmentation fault

The latest HEAD is segfaulting on startup if I have the following
lines in postgresql.conf:

custom_variable_classes = 'plperl'
plperl.use_strict = on

If I comment out the second line then the server starts successfully.
Platform is Solaris 9/sparc.

(gdb) bt
#0 0xff0340a0 in strcmp () from /usr/lib/libc.so.1
#1 0x00257504 in verify_config_option (name=0x0, value=0x397258 "on", context=PGC_POSTMASTER, source=PGC_S_FILE, isNewEqual=0xffbff2cb "\001",
isContextOK=0xffbff2ca "\001\001") at guc.c:5513
#2 0x0025d3b4 in ProcessConfigFile (context=PGC_POSTMASTER) at guc-file.l:152
#3 0x0025d80c in SelectConfigFiles (userDoption=0x1 <Address 0x1 out of bounds>, progname=0x390610 "postgres") at guc.c:2867
#4 0x0019a450 in PostmasterMain (argc=5, argv=0x391240) at postmaster.c:602
#5 0x001518c8 in main (argc=5, argv=0x391240) at main.c:187

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Michael Fuhr