GDB unable to load .dwo files

gistfile1.txt

$ echo -e '#include <iostream>\nint main() { std::cout << "test\\n"; return 0; }' > main.cpp

$ g++ -fuse-ld=gold -gsplit-dwarf -Wl,--gdb-index main.cpp

$ ls
a.out  main.cpp  main.dwo

$ gdb a.out
GNU gdb (GDB) 8.2.1
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Reading symbols from a.out...done.
BFD: /home/coates/source/gdb-dwo-test/main.dwo: unable to initialize decompress status for section .debug_info.dwo
BFD: /home/coates/source/gdb-dwo-test/main.dwo: unable to initialize decompress status for section .debug_info.dwo
BFD: /home/coates/source/gdb-dwo-test/main.dwo: unable to initialize decompress status for section .debug_info.dwo
BFD: /home/coates/source/gdb-dwo-test/main.dwo: unable to initialize decompress status for section .debug_info.dwo

warning: Could not find DWO CU main.dwo(0x4665f77b086b112) referenced by CU at offset 0x0 [in module /home/coates/source/gdb-dwo-test/a.out]
(gdb) quit

$ g++ --version
g++ (GCC) 8.2.1 20181127
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.