History expansion in multiline string, within single quote

[schplurtz]

Configuration Information [Automatically generated, do not change]: 
Machine: x86_64 
OS: linux-gnu 
Compiler: gcc 
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' 
-DCONF_VENDOR='pc' - 
DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -I. 
-I../. -I.././include -I.././lib -Wdate-time -D_FORTIFY_SOURCE=2 -g 
-O2 -fdebug-prefix-map=/build/bash-7fckc0/bash-4.4=. -fstack-protector-strong 
-Wformat -Werror=format-security -Wall -no-pie -Wno-parentheses -Wno 
-format-security 
uname output: Linux vmsch003 4.9.0-7-amd64 #1 SMP Debian 4.9.110-3+deb9u1 
(2018-08-03) x86_64 GNU/Linux 
Machine Type: x86_64-pc-linux-gnu 

Bash Version: 4.4 
Patch Level: 12 
Release Status: release 

Description: 
Bug happens in an interactive shell. 

this works as expected, no history expansion : 
echo "foo"'!bar'"qux" 

but this fails, bash tries to hist-expand !bar', which it should not. 
echo "foo 
"'!bar'"qux" 

-bash: !bar': event not found 

I just compiled bash 4.4.18 and tested, the bug is there too.