Simpify std/png "yield short read" loop
diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index 1d5298d..9a3f8c8 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -40554,9 +40554,8 @@
               wuffs_png__decoder__filter_and_swizzle(self, a_dst, wuffs_base__slice_u8__subslice_j(a_workbuf, self->private_impl.f_workbuf_wi));
             }
             while (true) {
-              status = v_status;
+              status = wuffs_base__make_status(wuffs_base__suspension__short_read);
               WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(6);
-              v_status = wuffs_base__make_status(wuffs_base__suspension__short_read);
             }
           }
           status = v_status;
diff --git a/std/png/decode_png.wuffs b/std/png/decode_png.wuffs
index 7f9d37f..f66fae2 100644
--- a/std/png/decode_png.wuffs
+++ b/std/png/decode_png.wuffs
@@ -1209,8 +1209,7 @@
 						this.filter_and_swizzle!(dst: args.dst, workbuf: args.workbuf[.. this.workbuf_wi])
 					}
 					while true {
-						yield? status
-						status = base."$short read"
+						yield? base."$short read"
 					} endwhile
 				}
 				yield? status