repoman/MANIFEST.in: include .repoman_not_installed

Suggested-by: Arfrever Frehtes Taifersar Arahesis <arfrever.fta@gmail.com>
diff --git a/repoman/MANIFEST.in b/repoman/MANIFEST.in
index ed81a97..d9ef2ae 100644
--- a/repoman/MANIFEST.in
+++ b/repoman/MANIFEST.in
@@ -1,3 +1,4 @@
 
 # for the tests
 include cnf/metadata.xsd
+include .repoman_not_installed