ASSERT code_api|client.thread sporadic failure on Travis: lock->owner == d_r_get_thread_id()

From https://travis-ci.com/DynamoRIO/dynamorio/jobs/189723041

code_api|client.thread .......................................***Failed  Required regular expression not found.Regex=[^PR 216931: client options are -paramx -paramy
inside app client\.thread\.exe
PR 198871 locking test\.\.\.\.\.\.passed
client thread is alive
event_timer fired
client thread is dying
PR 222812: client thread test passed
PR 210591: testing client transparency
client thread is alive
event_timer fired
thank you for testing the client interface
TLS slot 0 is 0x00000000badcab42
TLS slot 1 is 0x00000000badcab43
TLS slot 2 is 0x00000000badcab44
TLS slot 3 is 0x00000000badcab45
process is exiting
client thread is dying
$
] 90.00 sec
PR 216931: client options are -paramx -paramy
inside app client.thread.exe
PR 198871 locking test......passed
<Application /home/travis/build/DynamoRIO/dynamorio/build_debug-internal-64/suite/tests/bin/client.thread (20820).  Internal Error: DynamoRIO debug check failure: /home/travis/build/DynamoRIO/dynamorio/core/utils.c:667 lock->owner == d_r_get_thread_id()
(Error occurred @0 frags)
version 7.1.17988, custom build
-no_dynamic_options -client_lib '/home/travis/build/DynamoRIO/dynamorio/build_debug-internal-64/suite/tests/bin/libclient.thread.dll.so;0;"-paramx" "-paramy"' -code_api -stderr_mask 12 -stack_size 56K -signal_stack_size 32K -max_elide_jmp 0 -max_elide_call 0 -early_inject -emulate_brk -no_inline_ignored_syscalls -native_
0x000000004e3a1210 0x00007f83f304b380
0x000000004e3a1460 0x00007f83f304d84b
0x000000004e3a14a0 0x00007f83f304deb7
0x000000004e3a14d0 0x00007f83f30da3dc
0x000000004e3a15c0 0x00007f83f30db5a2
0x000000004e3a1620 0x00007f83f30de41c
0x000000004e3a16f0 0x00007f83f30decf8
0x000000004e3a17b0 0x00007f83f30df1dc
0x000000004e3a17e0 0x00007f83f30e0a35
0x000000004e3a1800 0x00007f83f3212e7f
0x000000004e3a1820 0x00007f83f2fc4464
0x000000004e3a1870 0x00007f83f3216ab9
0x000000004e3a18b0 0x00007f83f31f8650
0x000000004e375910 0x000000007200193a
0x000000004e375980 0x00007f83f314dd76
/home/travis/build/DynamoRIO/dynamorio/build_debug-internal-64/suite/tests/bin/libclient.thread.dll.so=0x0000000072000000
/lib/x86_64-linux-gnu/libc.so.6=0x00007f83f298d000
/lib64/ld-linux-x86-64.so.2=0x00007f83f2764000>