Looks like we need an even older Gun version

Oops!

Makefile

@@ -16,7 +16,7 @@ CI_OTP = OTP_R16B01 OTP_R16B02 OTP_R16B03-1 OTP-17.0.2 OTP-17.1.2 OTP-17.2.2 OTP
 DEPS = cowlib ranch
 TEST_DEPS = ct_helper gun
 dep_ct_helper = git https://github.com/extend/ct_helper.git master
-dep_gun = git https://github.com/ninenines/gun 0b2d73c1d70dfe1c291daa3211ace022cfa765a2
+dep_gun = git https://github.com/ninenines/gun b85c1f726ca49ac0e3abdcf717317cb95b06207d
 
 # Standard targets.