[dmd-internals] Fixing github pull requests that I borked up

[Walter Bright]

An example:

     https://github.com/D-Programming-Language/dmd/pull/2615

See all those extra commits in there? That's because I did a:

     git push -f

from the wrong branch. Git, miserable program that it is, has no:

     git undo

which it so desperately needs. Anyhow, this royally borked up github. Brad 
Roberts came riding the rescue, and got the damage to the main repo undone. 
However, the PR's did not fix themselves.

However, I discovered that if I:

     git checkout myfixbranch
     git commit --amend -a
     git push -f

for my PR's, one by one, it fixed the PR's. So I fixed mine, but y'all will 
likely each have to fix yours one by one. Brad has an email in to github support 
to see if this can be fixed without needing each of us to do it, but in the 
meantime, or if that doesn't pan out, this should work.

Sorry about this.