update: job ID must be positive

The documentation for directory_update_init() was incorrect: a job ID
must be positive, not non-negative.  If the update queue is full and
no job was created, it makes more sense to return 0 instead of -1,
because it is more consistent with the return value of isUpdatingDB().

1 files changed, 2 insertions, 2 deletions

diff --git a/src/update.h b/src/update.h
index 0c0d74416..5c7277e32 100644
--- a/src/update.h
+++ b/src/update.h
@@ -23,8 +23,8 @@
 int isUpdatingDB(void);
 
 /*
- * returns the non-negative update job ID on success,
- * returns -1 if busy
+ * returns the positive update job ID on success,
+ * returns 0 if busy
  * @path will be freed by this function and should not be reused
  */
 int directory_update_init(char *path);