[Bug c++/55922] brace initializing parent cause bogus virtual base constructor calls

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55922

--- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The testcase in comment 1 originally made three calls to _ZN4BaseC2Ev until 
r238688 when it made two, and then only one call after r238689 (the fix for PR
66617).

So it looks like the reason it's still wrong on gcc-6-branch is that r238689
isn't on the branch.