Fix crash on long empty string

bugbear.py

@@ -72,7 +72,7 @@ def gen_line_based_checks(self):
                 continue
 
             length = len(line) - 1
-            if length > 1.1 * self.max_line_length:
+            if length > 1.1 * self.max_line_length and line.strip():
                 # Special case long URLS and paths to follow pycodestyle.
                 # Would use the `pycodestyle.maximum_line_length` directly but
                 # need to supply it arguments that are not available so chose

tests/b950.py

@@ -19,3 +19,8 @@
 
 # This
 #                                                                      almost_empty_line_too_long
+
+# Long empty line
+"""
+
+"""