completion: Add completion/custom.completion.bash to .gitignore.
diff --git a/.gitignore b/.gitignore
index b27cddd..dc86810 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,7 @@
 !custom/example.bash
 .rvmrc
 aliases/custom.aliases.bash
+completion/custom.completion.bash
 lib/custom.bash
 plugins/custom.plugins.bash
 *.swp