UglifyJS version 3.4.9 changes behavior of code.

[MR-fisher]

Bug report

Uglify version 3.4.9

JavaScript input

// test.js
var a, b, c;
function test() {
  console.log(arguments[0])
}
if (1 == c) {
  a = 1;
  b = 2;
} else {
  a = 0;
  b = 1;
}
test(a, b, 3);

The uglifyjs CLI command executed or minify() options used.

uglifyjs test.js -c -m -o test.min.js

JavaScript output or error produced.

// test.min.js
var a,b,c;function test(){console.log(arguments[0])}test(a,b=1==c?(a=1,2):(a=0,1),3);

Expect the console to print 0, but actually print undefined.

Sorry my english.