test/fixedbugs: add test for #19403
test/fixedbugs: add test for #19403

Change-Id: Ie52dac8eb4daed95e049ad74d5ae101e8a5cb854
Reviewed-on: https://go-review.googlesource.com/37725
Run-TryBot: Quentin Smith <d6b8e48afb2534b213e391cab43016505747a234@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>

linux-on-ibm-z/go,polyverse-security/go,josharian/go,nawawi/go,CAFxX/go,golang/go,Cofyc/go,josharian/go,vsekhar/elastic-go,nawawi/go,derekmarcotte/go,vsekhar/elastic-go,nawawi/go,golang/go,nawawi/go,christopher-henderson/Go,linux-on-ibm-z/go,derekmarcotte/go,nawawi/go,josharian/go,CAFxX/go,ImJasonH/go,linux-on-ibm-z/go,derekmarcotte/go,Cofyc/go,akutz/go,polyverse-security/go,linux-on-ibm-z/go,codestation/go,linux-on-ibm-z/go,vsekhar/elastic-go,akutz/go,derekmarcotte/go,CAFxX/go,Cofyc/go,CAFxX/go,CAFxX/go,CAFxX/go,Cofyc/go,codestation/go,codestation/go,CAFxX/go,akutz/go,golang/go,ImJasonH/go,golang/go,akutz/go,cloudflare/go,polyverse-security/go,vsekhar/elastic-go,akutz/go,vsekhar/elastic-go,golang/go,cloudflare/go,josharian/go,golang/go,polyverse-security/go,derekmarcotte/go,ImJasonH/go,cloudflare/go,Cofyc/go,Cofyc/go,vsekhar/elastic-go,derekmarcotte/go,cloudflare/go,golang/go,ImJasonH/go,polyverse-security/go,ImJasonH/go,akutz/go,linux-on-ibm-z/go,golang/go,codestation/go,Cofyc/go,polyverse-security/go,codestation/go,linux-on-ibm-z/go,linux-on-ibm-z/go,nawawi/go,josharian/go,cloudflare/go,codestation/go,ImJasonH/go,ImJasonH/go,vsekhar/elastic-go,josharian/go,cloudflare/go,polyverse-security/go,nawawi/go,derekmarcotte/go,codestation/go,nawawi/go,cloudflare/go,ImJasonH/go,polyverse-security/go,josharian/go,cloudflare/go,josharian/go,derekmarcotte/go,vsekhar/elastic-go,CAFxX/go,Cofyc/go,akutz/go,akutz/go,codestation/go