more max_rows behavior matching

Author: kandersolar

pvlib/bifacial/utils.py

@@ -243,8 +243,9 @@ def vf_ground_sky_2d_integ(surface_tilt, gcr, height, pitch, max_rows=10,
     collector_width = pitch * gcr
     surface_tilt = np.atleast_2d(np.abs(surface_tilt))
 
-    # TODO figure out if this range is correct, or if the original code has a bug
-    k = np.arange(-max_rows+1, max_rows+1)[:, np.newaxis]
+    # TODO seems like this should be np.arange(-max_rows, max_rows+1)?
+    # see GH #1867
+    k = np.arange(-max_rows, max_rows)[:, np.newaxis]
 
     # primary crossed string points:
     # a, b: boundaries of ground segment