Avoid grouping components when they lack the grouping fields.

- This is for the internal BoM when `merge_blank_fields` is disabled

CHANGELOG.md

@@ -26,6 +26,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   Can be disabled to use absolute coordinates. (#87)
 - Board View: flipped output. (#89)
 - Board View: problems with netnames using spaces. (#90)
+- Internal BoM: When `merge_blank_fields` is disabled and we compare two empty
+  fields now we avoid a match. So we don't group undefined components.
+
 
 ## [0.11.0] - 2021-04-25
 ### Added

kibot/bom/bom.py

@@ -70,6 +70,9 @@ def compare_field(c1, c2, field, cfg):
     # If blank comparisons are allowed
     if (c1_value == "" or c2_value == "") and cfg.merge_blank_fields:
         return True
+    if not cfg.merge_blank_fields and c1_value == "" and c2_value == "":
+        # Avoid merging two components with empty field
+        return False
     return c1_value == c2_value