The macros option of addPatch

Here is a subtle problem you may encounter when your package needs a patch.
{code}

First, here is how the patch is added in the recipe. Notice macros=True
{code}
         r.addPatch('servicedir.patch', macros=True,
                   use=(r.macros.servicedir != '/var'))
{code}
Then, please take a look at the right patch,
{code}
 --- camel/providers/local/camel-local-folder.c    2009-05-06 03:59:32.000000000 -0500
+++ camel/providers/local/camel-local-folder.c    2009-05-06 03:58:29.000000000 -0500
@@ -391,8 +391,8 @@
                     /* $HOME relative path + protocol string */
                     folder->description = g_strdup_printf(_("~%%s (%%s)"), path+strlen(tmp),
                                           ((CamelService *)folder->parent_store)->url->protocol);
-                else if ((tmp = "/var/spool/mail") && strncmp(tmp, path, strlen(tmp)) == 0)
-                    /* /var/spool/mail relative path + protocol */
+                else if ((tmp = "%(servicedir)s/spool/mail") && strncmp(tmp, path, strlen(tmp)) == 0)
+                    /* %(servicedir)s/spool/mail relative path + protocol */
                     folder->description = g_strdup_printf(_("mailbox: %%s (%%s)"), path+strlen(tmp),
                                           ((CamelService *)folder->parent_store)->url->protocol);
                 else if ((tmp = "/var/mail") && strncmp(tmp, path, strlen(tmp)) == 0)
{code}
and the wrong one. Look hard to find out the difference :-)
{code}
 --- camel/providers/local/camel-local-folder.c    2009-05-06 03:59:32.000000000 -0500
+++ camel/providers/local/camel-local-folder.c    2009-05-06 03:58:29.000000000 -0500
@@ -391,8 +391,8 @@
                     /* $HOME relative path + protocol string */
                     folder->description = g_strdup_printf(_("~%s (%s)"), path+strlen(tmp),
                                           ((CamelService *)folder->parent_store)->url->protocol);
-                else if ((tmp = "/var/spool/mail") && strncmp(tmp, path, strlen(tmp)) == 0)
-                    /* /var/spool/mail relative path + protocol */
+                else if ((tmp = "%(servicedir)s/spool/mail") && strncmp(tmp, path, strlen(tmp)) == 0)
+                    /* %(servicedir)s/spool/mail relative path + protocol */
                     folder->description = g_strdup_printf(_("mailbox: %s (%s)"), path+strlen(tmp),
                                           ((CamelService *)folder->parent_store)->url->protocol);
                 else if ((tmp = "/var/mail") && strncmp(tmp, path, strlen(tmp)) == 0)
{code}
"%s" \!\! Conary would think this is also a macro and tries to substitute it and, of course, trigger a python exception somewhere.

So if you are using "macros" in your patch, take a moment to update the non-macros, like %s.