Filter pins out of solver output

libmamba/src/core/solver.cpp

@@ -226,13 +226,18 @@ namespace mamba
         // Solvable need to provide itself
         cons_solv.add_self_provide();
 
+        // Even if we lock it, libsolv may still try to remove it with
+        // `SOLVER_FLAG_ALLOW_UNINSTALL`, so we flag it as not a real package to filter it out in
+        // the transaction
+        cons_solv.set_artificial(true);
+
         // Necessary for attributes to be properly stored
         installed->internalize();
 
         // Lock the dummy solvable so that it stays install.
         // Force verify the dummy solvable dependencies, as this is not the default for
         // installed packages.
-        return add_jobs({ cons_solv_name }, SOLVER_LOCK & SOLVER_VERIFY);
+        return add_jobs({ cons_solv_name }, SOLVER_LOCK | SOLVER_VERIFY);
     }
 
     void MSolver::add_pins(const std::vector<std::string>& pins)

libmamba/src/core/transaction.cpp

@@ -147,6 +147,18 @@ namespace mamba
                 [&](const solv::SolvableId id)
                 {
                     auto pkginfo = get_pkginfo(id);
+
+                    // Artificial packages are packages that were added to implement a feature
+                    // (e.g. a pin) but do not represent a Conda package.
+                    // They can appear in the transaction depending on libsolv flags.
+                    // We use this attribute to filter them out.
+                    if (const auto solv = pool.pool().get_solvable(id);
+                        solv.has_value() && solv->artificial())
+                    {
+                        LOG_DEBUG << "Solution: Remove artificial " << pkginfo.str();
+                        return;
+                    }
+
                     // keep_only ? specs.contains(...) : !specs.contains(...);
                     // TODO ideally we should use Matchspecs::contains(pkginfo)
                     if (keep_only == specs.contains(pkginfo.name))