Try running no-chroot commands in env rather than sh -c.

src/libcalamares/utils/CalamaresUtilsSystem.cpp

@@ -149,8 +149,7 @@ System::targetEnvOutput( const QStringList& args,
     }
     else
     {
-        program = "sh";
+        program = "env";
-        arguments = QStringList( { "-c" } );
         arguments << args.join( ' ' );
     }