Fix docstring of gnus-dependencies-add-header

* lisp/gnus/gnus-sum.el (gnus-dependencies-add-header): Code is
  correct, but docs had logic of `gnus-summary-ignore-duplicates'
  backwards: if it's t, the Message-IDs will not be renamed.

1 files changed, 4 insertions, 4 deletions

diff --git a/lisp/gnus/gnus-sum.el b/lisp/gnus/gnus-sum.el
index e562b30170a..ceb98421665 100644
--- a/lisp/gnus/gnus-sum.el
+++ b/lisp/gnus/gnus-sum.el
@@ -4310,10 +4310,10 @@ If SELECT-ARTICLES, only select those articles from GROUP."
 If FORCE-NEW is not nil, enter HEADER into the DEPENDENCIES table even
 if it was already present.
 
-If `gnus-summary-ignore-duplicates' is nil then duplicate Message-IDs
-will not be entered in the DEPENDENCIES table.  Otherwise duplicate
-Message-IDs will be renamed to a unique Message-ID before being
-entered.
+If `gnus-summary-ignore-duplicates' is non-nil then duplicate
+Message-IDs will not be entered in the DEPENDENCIES table.
+Otherwise duplicate Message-IDs will be renamed to a unique
+Message-ID before being entered.
 
 Returns HEADER if it was entered in the DEPENDENCIES.  Returns nil otherwise."
   (let* ((id (mail-header-id header))