Regression: Unnecessary parens with unary minus operator

[JelleZijlstra]

I noticed this change while testing Black master on our codebase:

             step_adjustments["ScalingAdjustment"] = min(
-                scaling_adjustment, -self.get_max_weight()
+                scaling_adjustment, -(self.get_max_weight())
             )

Also (more justifiable):

-        -2 ** 32,
-        -2 ** 48,
-        -2 ** 63,
+        -(2 ** 32),
+        -(2 ** 48),
+        -(2 ** 63),

I think the first example is a bug. A simpler repro:

$ black -c '-self.x()'
-(self.x())

[hugovk]

A few other examples, running master on a pre-Blackened codebase:

-        for y in range(-1, -im1.size[1] - 1, -1):
-            for x in range(-1, -im1.size[0] - 1, -1):
+        for y in range(-1, -(im1.size[1]) - 1, -1):
+            for x in range(-1, -(im1.size[0]) - 1, -1):

-        angle = -math.radians(deg)
+        angle = -(math.radians(deg))
         matrix = [
             round(math.cos(angle), 15),
             round(math.sin(angle), 15),
             0.0,
-            round(-math.sin(angle), 15),
+            round(-(math.sin(angle)), 15),
             round(math.cos(angle), 15),
             0.0,
             0,

-        code, = struct.unpack_from("<I", block, 12)
+        (code,) = struct.unpack_from("<I", block, 12)

-        angle = -math.radians(angle)
+        angle = -(math.radians(angle))
         matrix = [
             round(math.cos(angle), 15),
             round(math.sin(angle), 15),
             0.0,
-            round(-math.sin(angle), 15),
+            round(-(math.sin(angle)), 15),

-                dest[tag], = values
+                (dest[tag],) = values

With some comment mangling:

         if self.magic == b"BLP1":
-            # Only present for BLP1
-            self._blp_encoding, = struct.unpack("<i", self.fp.read(4))
-            self._blp_subtype, = struct.unpack("<i", self.fp.read(4))
+            (self._blp_encoding,) = struct.unpack(  # Only present for BLP1
+                "<i", self.fp.read(4)
+            )
+            (self._blp_subtype,) = struct.unpack("<i", self.fp.read(4))

[JelleZijlstra]

That last one looks like a separate regression. It doesn't make sense for Black to move that comment.

[JelleZijlstra]

Also, the tuple unpacking thing (your (code,) = example) is an intentional change from #832.