Mention that DEBUG_LEAK includes DEBUG_SAVEALL. Fixes #1170460.
Will backport to 2.4.
diff --git a/Doc/lib/libgc.tex b/Doc/lib/libgc.tex
index 30939f0..e53e2a8 100644
--- a/Doc/lib/libgc.tex
+++ b/Doc/lib/libgc.tex
@@ -14,7 +14,9 @@
 can disable the collector if you are sure your program does not create
 reference cycles.  Automatic collection can be disabled by calling
 \code{gc.disable()}.  To debug a leaking program call
-\code{gc.set_debug(gc.DEBUG_LEAK)}.
+\code{gc.set_debug(gc.DEBUG_LEAK)}. Notice that this includes 
+\code{gc.DEBUG_SAVEALL}, causing garbage-collected objects to be
+saved in gc.garbage for inspection.
 
 The \module{gc} module provides the following functions: