From e48983132cf3e5adec2eb31a869127aab3aa9430 Mon Sep 17 00:00:00 2001
From: Owen W. Taylor <otaylor@fishsoup.net>
Date: Apr 29 2022 19:47:08 +0000
Subject: Clarify the meaning conf.allow_only_compatible_base_modules=False


config.allow_compatible_base_modules=False does different things for
build-requires selection and for module reuse. Clarify this in the config
key documentation.

(This config key is really: True: "do what RHEL expects"
False: "do what Fedora expects")

---

diff --git a/module_build_service/common/config.py b/module_build_service/common/config.py
index ea6ad0f..6e71fd9 100644
--- a/module_build_service/common/config.py
+++ b/module_build_service/common/config.py
@@ -440,8 +440,12 @@ class Config(object):
             "type": bool,
             "default": True,
             "desc": "When True, only modules built on top of compatible base modules are "
-                    "considered by MBS as possible buildrequirement. When False, modules "
-                    "built against any base module stream can be used as a buildrequire.",
+                    "considered by MBS as possible buildrequirement or as a reuse candidate. "
+                    "When False, modules built against any base module stream sharing a "
+                    "virtual stream can be used as a buildrequire, but only modules built "
+                    "against the exact same base module stream are considered as candidates "
+                    "for reuse. Setting this to True requires base module streams to be of the "
+                    " form: <prefix><x>.<y>.<z>.",
         },
         "base_module_stream_exclusions": {
             "type": list,
diff --git a/module_build_service/scheduler/reuse.py b/module_build_service/scheduler/reuse.py
index 0af9f61..06ecde1 100644
--- a/module_build_service/scheduler/reuse.py
+++ b/module_build_service/scheduler/reuse.py
@@ -83,7 +83,9 @@ def get_reusable_module(module):
     #
     # 1) The `conf.allow_only_compatible_base_modules` is False. This means that MBS should
     #    not try to find any compatible base modules in its DB and simply use the buildrequired
-    #    base module as it is.
+    #    base module as it is. (*NOTE* This is different than the meaning of
+    #    allow_only_compatible_base_modules=False when looking up build requirements - where
+    #    it means to accept any module buildrequiring a base modul sharing a virtual stream.)
     # 2) The `conf.allow_only_compatible_base_modules` is True and DBResolver is used. This means
     #    that MBS should try to find the compatible modules using its database.
     #    The `get_base_module_mmds` finds out the list of compatible modules and returns mmds of