Fix segfault accessing file handle in test_tiered08

Program terminated with signal SIGSEGV, Segmentation fault.

#0  __wt_read (buf=0xaaab02145640, len=4096, offset=1748992, fh=0xabababababababab, 

    session=0xaaab00c91770) at ../src/include/os_fhandle_inline.h:116

116	    ret = fh->handle->fh_read(fh->handle, (WT_SESSION *)session, offset, len, buf);

[Current thread is 1 (Thread 0xffffb3a5a010 (LWP 107361))]

(gdb) print fh

$1 = (WT_FH *) 0xabababababababab

(gdb) bt

#0  __wt_read (buf=0xaaab02145640, len=4096, offset=1748992, fh=0xabababababababab, 

    session=0xaaab00c91770) at ../src/include/os_fhandle_inline.h:116

#1  __wt_block_read_off (session=session@entry=0xaaab00c91770, block=<optimized out>, 

    block@entry=0xffff30d65580, buf=buf@entry=0xfffff63e40b8, objectid=15, offset=1748992, 

    size=4096, checksum=104540736) at ../src/block/block_read.c:195

#2  0x0000ffffb2ae8de4 in __wt_bm_read (bm=0xaaab00465ad0, session=0xaaab00c91770, 

    buf=0xfffff63e40b8, addr=<optimized out>, addr_size=<optimized out>)

    at ../src/block/block_read.c:41

#3  0x0000ffffb2af0968 in __bm_read (bm=<optimized out>, session=<optimized out>, 

    buf=<optimized out>, addr=<optimized out>, addr_size=<optimized out>)

    at ../src/block_cache/block_mgr.c:486

#4  0x0000ffffb2aeed58 in __wt_blkcache_read (session=session@entry=0xaaab00c91770, 

    buf=buf@entry=0xfffff63e40b8, addr=addr@entry=0xfffff63e40e1 "\301j\201\344\006;\n", 

    addr_size=10) at ../src/block_cache/block_io.c:111

#5  0x0000ffffb2b3f600 in __page_read (session=session@entry=0xaaab00c91770, 

    ref=ref@entry=0xaaab00f51d50, flags=flags@entry=128) at ../src/btree/bt_read.c:183

#6  0x0000ffffb2b40184 in __wt_page_in_func (session=session@entry=0xaaab00c91770, 

    ref=ref@entry=0xaaab00f51d50, flags=flags@entry=128, 

    func=func@entry=0xffffb2d14270 <__PRETTY_FUNCTION__.39457> "__wt_row_search", 

    line=line@entry=438) at ../src/btree/bt_read.c:307

#7  0x0000ffffb2b8460c in __wt_page_swap_func (line=438, 

    func=0xffffb2d14270 <__PRETTY_FUNCTION__.39457> "__wt_row_search", flags=128, 

    want=0xaaab00f51d50, held=0xffffa00aa2c0, session=0xaaab00c91770)

    at ../src/include/btree_inline.h:2150

#8  __wt_row_search (cbt=cbt@entry=0xaaab058b2bc0, srch_key=srch_key@entry=0xaaab058b2cd8, 

    insert=insert@entry=true, leaf=leaf@entry=0x0, leaf_safe=leaf_safe@entry=false, 

    leaf_foundp=leaf_foundp@entry=0x0) at ../src/btree/row_srch.c:438

#9  0x0000ffffb2b0f9c4 in __cursor_row_search (leaf_foundp=0x0, leaf=0x0, insert=true, 

    cbt=0xaaab058b2bc0) at ../src/btree/bt_cursor.c:501

#10 __wt_btcur_insert (cbt=cbt@entry=0xaaab058b2bc0) at ../src/btree/bt_cursor.c:1161

#11 0x0000ffffb2bc169c in __curfile_insert (cursor=0xaaab058b2bc0) at ../src/cursor/cur_file.c:384

#12 0x0000ffffb2db1c14 in _wrap_Cursor_insert (self=<optimized out>, args=<optimized out>)

    at lang/python/CMakeFiles/wiredtiger_python.dir/wiredtigerPYTHON_wrap.c:4083