bdiff: fix malloc(0) issue in fixws()
If fixws() is called on a zero-length string, malloc(0) is called and
expected to return a pointer. Which it does on e.g. Linux. AIX returns
NULL, which it is also legal, but the malloc() is then assumed to have
failed. So ensure a valid pointer is always returned.
Test the GPG extension
$ "$TESTDIR/hghave" gpg || exit 80
$ cat <<EOF >> $HGRCPATH
> [extensions]
> gpg=
>
> [gpg]
> cmd=gpg --no-permission-warning --no-secmem-warning --homedir $TESTDIR/gpg
> EOF
$ hg init r
$ cd r
$ echo foo > foo
$ hg ci -Amfoo
adding foo
$ hg sigs
$ hg sign 0
Signing 0:e63c23eaa88a
$ hg sigs
hgtest 0:e63c23eaa88ae77967edcf4ea194d31167c478b0
$ hg sigcheck 0
e63c23eaa88a is signed by:
hgtest