Change page deletion assert condition in __split_insert()

[1584974735:984619][16062:0x7ff8c67fc700], t, file:wt, WT_CURSOR.insert: __split

_insert, 1722: unexpected page-delete structure when splitting a page: WT_PANIC:

 WiredTiger library panic

(gdb) bt

#0  0x00007ff8e3df45f7 in raise () from /lib64/libc.so.6

#1  0x00007ff8e3df5ce8 in abort () from /lib64/libc.so.6

#2  0x000000000049ae8e in __wt_abort (session=0x1aa0b08) at ../src/os_common/os_abort.c:30

#3  0x000000000057c3ad in __split_insert (session=0x1aa0b08, ref=0x7ff8901db460) at ../src/btree/bt_split.c:1721

#4  0x000000000057cf5e in __split_insert_lock (session=0x1aa0b08, ref=0x7ff8901db460) at ../src/btree/bt_split.c:1993

#5  0x000000000057d01d in __wt_split_insert (session=0x1aa0b08, ref=0x7ff8901db460) at ../src/btree/bt_split.c:2020

#6  0x00000000004722e1 in __evict_review (session=0x1aa0b08, ref=0x7ff8901db460, evict_flags=4, inmem_splitp=0x7ff8c67fb9c3)

    at ../src/evict/evict_page.c:589

#7  0x0000000000470a8d in __wt_evict (session=0x1aa0b08, ref=0x7ff8901db460, previous_state=3 '\003', flags=4) at ../src/evict/evict_page.c:176

#8  0x00000000004707d0 in __wt_page_release_evict (session=0x1aa0b08, ref=0x7ff8901db460, flags=0) at ../src/evict/evict_page.c:81

#9  0x00000000005628cc in __wt_page_in_func (session=0x1aa0b08, ref=0x7ff8901db460, flags=1024, func=0x644600 <__func__.18250> "__wt_row_search", 

    line=425) at ../src/btree/bt_read.c:341

#10 0x00000000005977dc in __wt_page_swap_func (session=0x1aa0b08, held=0x3236810, want=0x7ff8901db460, flags=1024, 

    func=0x644600 <__func__.18250> "__wt_row_search", line=425) at ../src/include/btree.i:1657

#11 0x0000000000598e37 in __wt_row_search (cbt=0x7ff84c1ce570, srch_key=0x7ff84c1ce670, insert=true, leaf=0x0, leaf_safe=false, leaf_foundp=0x0)

    at ../src/btree/row_srch.c:425

#12 0x00000000005439e4 in __cursor_row_search (cbt=0x7ff84c1ce570, insert=true, leaf=0x0, leaf_foundp=0x0) at ../src/btree/bt_cursor.c:383

#13 0x0000000000544fd0 in __wt_btcur_insert (cbt=0x7ff84c1ce570) at ../src/btree/bt_cursor.c:866

#14 0x0000000000450ec7 in __curfile_insert (cursor=0x7ff84c1ce570) at ../src/cursor/cur_file.c:265

#15 0x000000000040cad0 in row_insert (tinfo=0x3bda1c0, cursor=0x7ff84c1ce570, positioned=false) at ../../../test/format/ops.c:1553

#16 0x0000000000409e7d in ops (arg=0x3bda1c0) at ../../../test/format/ops.c:733

#17 0x00007ff8e47aedc5 in start_thread () from /lib64/libpthread.so.0