Test client.drmgr-test failing with "signal not correct" on modern Linux machine.

The test fails deterministically every time:

gcc --version gcc (Debian 7.3.0-5) 7.3.0

cat /proc/version Linux version 4.19.20-1rodete1-amd64 [..]

cat /proc/cpuinfo [..] processor : 11 vendor_id : GenuineIntel cpu family : 6 model : 85 model name : Intel(R) Xeon(R) W-2135 CPU @ 3.70GHz [..]

ctest -V -I 176,176
UpdateCTestConfiguration  from :/usr/local/google/home/hgreving/dynamorio/build/DartConfiguration.tcl
Parse Config file:/usr/local/google/home/hgreving/dynamorio/build/DartConfiguration.tcl
UpdateCTestConfiguration  from :/usr/local/google/home/hgreving/dynamorio/build/DartConfiguration.tcl
Parse Config file:/usr/local/google/home/hgreving/dynamorio/build/DartConfiguration.tcl
Test project /usr/local/google/home/hgreving/dynamorio/build
Constructing a list of tests
Done constructing a list of tests
Updating test list for fixtures
Added 0 tests to meet fixture requirements
Checking test dependency graph...
Checking test dependency graph end
test 176
    Start 176: code_api|client.drmgr-test

176: Test command: /usr/local/google/home/hgreving/dynamorio/build/bin64/drrun "-s" "90" "-quiet" "-debug" "-killpg" "-stderr_mask" "0xC" "-dumpcore_mask" "0" "-code_api" "-c" "/usr/local/google/home/hgreving/dynamorio/build/suite/tests/bin/libclient.drmgr-test.dll.so" "--" "/usr/local/google/home/hgreving/dynamorio/build/suite/tests/bin/client.drmgr-test" "/usr/local/google/home/hgreving/dynamorio/build/suite/tests/bin/libclient.events.appdll.so"
176: Test timeout computed to be: 1500
176: in event_thread_init_null_user_data
176: in event_thread_init_user_data
176: in event_thread_init_ex
176: in event_thread_init
176: in pre_sys_B_user_data
176: in pre_sys_B
176: in pre_sys_A_user_data
176: in pre_sys_A
176: in post_sys_B_user_data
176: in post_sys_B
176: in post_sys_A_user_data
176: in post_sys_A
176: B
176: Estimation of pi is 3.142425985001098
176: in signal_A_user_data
176: in signal_B_user_data
176: CHECK failed /usr/local/google/home/hgreving/dynamorio/src/suite/tests/client-interface/drmgr-test.dll.c:664: signal not correct
1/1 Test #176: code_api|client.drmgr-test .......***Failed  Required regular expression not found.Regex=[^in event_thread_init_null_user_data
in event_thread_init_user_data
in event_thread_init_ex
in event_thread_init
in pre_sys_B_user_data
in pre_sys_B
in pre_sys_A_user_data
in pre_sys_A
in post_sys_B_user_data
in post_sys_B
in post_sys_A_user_data
in post_sys_A
B
appdll initialized
Estimation of pi is 3.142425985001098
in signal_A_user_data
in signal_B_user_data
saw event_thread_exit
saw event_thread_exit_ex
saw event_thread_exit_user_data
saw event_thread_exit_null_user_data
saw event_mod_load
saw event_mod_unload
all done
$
]  0.39 sec

0% tests passed, 1 tests failed out of 1

Total Test time (real) =   1.85 sec

The following tests FAILED:
        176 - code_api|client.drmgr-test (Failed)