patch: fix segfault against unified diffs which start line is zero...
patch: fix segfault against unified diffs which start line is zero
Since 2b1ec74c961f, if a chunk starts with "@@ -0,1", oldstart turns into
a negative value. Because diffhelpers.testhunk() doesn't expect negative bstart,
it bypasses "alen > blen - bstart" condition and segfaults at
"PyList_GET_ITEM(b, i + bstart)".