Summary:
D51710654 seems to have broken this test by adding the error output. Let's update the test to be ok with the error output.

```
  --- test-sign-commit.t
    +++ test-sign-commit.t.err
    @@ -55,5 +55,10 @@
       updated config in $TESTTMP/repo1/.hg/hgrc
       $ echo 1 > delta
       $ hg commit -m gamma
    -  abort: error when running gpg with gpgkeyid foobar
    +  abort: error when running gpg with gpgkeyid foobar:
    +    gpg: skipped "foobar": No secret key
    +    [GNUPG:] INV_SGNR 9 foobar
    +    [GNUPG:] FAILURE sign 17
    +    gpg: signing failed: No secret key
    +
       [255]
```

Reviewed By: quark-zju, sggutier

Differential Revision: D52043451

fbshipit-source-id: 0751cfe76e39f0fb96637eb241c3af5d18e063f6