Another assert failure from no-palloc-in-critical-sections

I tried the test case given in
http://www.postgresql.org/message-id/dafad644f268ce1503e1b8b682aae38a.squirrel@webmail.xs4all.nl
on HEAD.  It asserted here:

#2  0x000000000077b419 in ExceptionalCondition (   conditionName=<value optimized out>, errorType=<value optimized
out>,   fileName=<value optimized out>, lineNumber=<value optimized out>)   at assert.c:54
 
#3  0x000000000079be76 in palloc (size=384) at mcxt.c:670
#4  0x0000000000479408 in ginCompressPostingList (ipd=0x7f13343bb048,    nipd=272428, maxsize=384,
nwritten=0x7fff1d832eec)at ginpostinglist.c:191
 
#5  0x000000000046b92b in createPostingTree (index=0x7f1348ae31e0,    items=0x7f13343bb048, nitems=272428,
buildStats=0x7fff1d835670)  at gindatapage.c:1739
 
#6  0x0000000000465206 in buildFreshLeafTuple (ginstate=0x7fff1d8330b0,    attnum=1, key=2105441, category=0 '\000',
items=0x7f13343bb048,   nitem=272428, buildStats=0x7fff1d835670) at gininsert.c:158
 
#7  ginEntryInsert (ginstate=0x7fff1d8330b0, attnum=1, key=2105441,    category=0 '\000', items=0x7f13343bb048,
nitem=272428,   buildStats=0x7fff1d835670) at gininsert.c:228
 
#8  0x0000000000465863 in ginbuild (fcinfo=<value optimized out>)   at gininsert.c:408
#9  0x0000000000784654 in OidFunctionCall3Coll (   functionId=<value optimized out>, collation=0, arg1=139720800461152,
  arg2=139720800481760, arg3=31056056) at fmgr.c:1650
 
#10 0x00000000004f18ba in index_build (heapRelation=0x7f1348ade160,    indexRelation=0x7f1348ae31e0,
indexInfo=0x1d9e0b8,isprimary=0 '\000',    isreindex=0 '\000') at index.c:1962
 
        regards, tom lane