bash-completion: fix bad array subscript error. Closes #6117

pkgs/shells/bash-completion/bash-4.3.patch

@@ -0,0 +1,22 @@
+commit a9c556ccad819869a6a5d932aac0a75a99372f08
+Author: Barry Warsaw <barry@python.org>
+Date:   Wed Sep 17 19:32:43 2014 +0300
+
+    _init_completion: Handle cword < 0 (LP: #1289597)
+    
+    Previously only bash 4.3 seemed to provoke this, but now with the
+    empty command consistency tweak it occurs with earlier as well.
+
+diff --git a/bash_completion b/bash_completion
+index 7e01ae4..3bb4bc2 100644
+--- a/bash_completion
++++ b/bash_completion
+@@ -727,7 +727,7 @@ _init_completion()
+         fi
+     done
+ 
+-    [[ $cword -eq 0 ]] && return 1
++    [[ $cword -le 0 ]] && return 1
+     prev=${words[cword-1]}
+ 
+     [[ ${split-} ]] && _split_longopt && split=true

pkgs/shells/bash-completion/default.nix

@@ -8,6 +8,8 @@ stdenv.mkDerivation rec {
     sha256 = "0kxf8s5bw7y50x0ksb77d3kv0dwadixhybl818w27y6mlw26hq1b";
   };
 
+  patches = [ ./bash-4.3.patch ];
+
   doCheck = true;
 
   meta = {