dhclient v4.4.1 - REQUIRE(ctx->running) assertion triggered on SIGTERM/SIGINT

name: REQUIRE(ctx->running) assertion triggered on SIGTERM/SIGINT
about: dhclient v4.4.1

Describe the bug
We noticed that sometimes, under heavy load, when SIGTERM/SIGINT is sent to dhclient, the following ASSERT is triggered:

...lib/isc/unix/app.c:574: REQUIRE(ctx->running) failed, back trace
#0 0x59355e in ??
#1 0x5936ea in ??
#2 0x5b4492 in ??
#3 0x7f20d70f0560 in ??
#4 0x7f20d71758f0 in ??
#5 0x7f20d71757a4 in ??
#6 0x42486c in ??
#7 0x40a39a in ??
#8 0x7f20d70dd6b0 in ??
#9 0x40ae39 in ??
Aborted

If the SIGTERM/SIGINT signal is sent during startup, in the small window interval between signal handler registration and the moment when ctx->running is set to 1, the REQUIRE(ctx->running) assertion is triggered.

Please let us know if any additional info is required.