update comments and add one FIXME for the next ABI break

apt-pkg/acquire-item.cc

@@ -1235,10 +1235,14 @@ void pkgAcqMetaIndex::Done(string Message,unsigned long long Size,string Hash,	/
       }
       else
       {
+         // FIXME: move this into pkgAcqMetaClearSig::Done on the next
+         //        ABI break
+
          // if we expect a ClearTextSignature (InRelase), ensure that
          // this is what we get and if not fail to queue a 
          // Release/Release.gpg, see #346386
-         if (SigFile == DestFile && !IsPgpClearTextSignature(DestFile))
+         if (SigFile == DestFile && 
+             !IsPgpClearTextSignature(DestFile))
          {
             Failed(Message, Cfg);
             return;

apt-pkg/contrib/fileutl.h

@@ -179,6 +179,7 @@ bool WaitFd(int Fd,bool write = false,unsigned long timeout = 0);
 pid_t ExecFork();
 bool ExecWait(pid_t Pid,const char *Name,bool Reap = false);
 
+// check if the given file starts with a PGP cleartext signature
 bool IsPgpClearTextSignature(std::string const &FileName);
 
 // File string manipulators