Travis failure on Linux in testset spawn

[stevengj]

We seem to be having problems on Travis (e.g. in #19305 and #19239) with a test failure on both 32-bit and 64-bit Linux, with an error message of the form:

Worker 11 failed running test spawn:
Some tests did not pass: 104 passed, 1 failed, 0 errored, 4 broken.
 in finish at ./test.jl:521
 in macro expansion at ./util.jl:288 [inlined]
 in runtests at /tmp/julia/share/julia/test/testdefs.jl:7
 in #644 at ./multi.jl:1446
 in run_work_thunk at ./multi.jl:1005
 in macro expansion at ./multi.jl:1446 [inlined]
 in #643 at ./event.jl:66spawn: Test Failed
  Expression: false
 in record(::Base.Test.DefaultTestSet, ::Base.Test.Fail) at ./test.jl:430
 in (::##33#40)() at /tmp/julia/share/julia/test/runtests.jl:138
 in cd(::##33#40, ::String) at ./file.jl:69
 in include_from_node1(::String) at ./loading.jl:532
 in include(::String) at ./sysimg.jl:14
 in process_options(::Base.JLOptions) at ./client.jl:271
 in _start() at ./client.jl:335

[yuyichao]

Dup of #19132