Explain various .self = false,

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>

src/libstore/binary-cache-store.cc

@@ -315,6 +315,7 @@ StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, std::string_view n
                 },
                 .references = {
                     .others = references,
+                    // caller is not capable of creating a self-reference, because this is content-addressed without modulus
                     .self = false,
                 },
             },
@@ -433,6 +434,7 @@ StorePath BinaryCacheStore::addToStore(
                 },
                 .references = {
                     .others = references,
+                    // caller is not capable of creating a self-reference, because this is content-addressed without modulus
                     .self = false,
                 },
             },

src/libstore/local-store.cc

@@ -1328,6 +1328,7 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name
         },
         .references = {
             .others = references,
+            // caller is not capable of creating a self-reference, because this is content-addressed without modulus
             .self = false,
         },
     };

src/nix/profile.cc

@@ -209,6 +209,7 @@ struct ProfileManifest
                 },
                 .references = {
                     .others = std::move(references),
+                    // profiles never refer to themselves
                     .self = false,
                 },
             },