Merge branch 'dl/complete-format-patch-recent-features'

Update to command line completion (in contrib/)

* dl/complete-format-patch-recent-features:
  contrib/completion: complete options that take refs for format-patch

Author: gitster

contrib/completion/git-completion.bash

@@ -1784,6 +1784,10 @@ _git_format_patch ()
 			" "" "${cur##--thread=}"
 		return
 		;;
+	--base=*|--interdiff=*|--range-diff=*)
+		__git_complete_refs --cur="${cur#--*=}"
+		return
+		;;
 	--*)
 		__gitcomp_builtin format-patch "$__git_format_patch_extra_options"
 		return