JDK-8272700 was created to fix a bug in a variable assignment in configure. While it fixed the bug, it kept the problematic syntax that caused the bug in the first place.

We do not use the "FOO+=appended" syntax for appending to variables in shell scripts, since this differs from what you'd expect (and what make produces) in that no space is added before the appended text.

Instead, we use the longer, but clearer "FOO=$FOO appended".