Add a function to get_url_json_unlimited to retrieve the total

The blueprints/changes API is a bit different from the others, the total
that it includes is for each blueprint, not one total for all of them,
since there will be a different number of commits for each.

The function is passed the dict, and it can be used to select the total
to use for retrieving all of the results. If it isn't included it will
use data["total"] which works fine in most cases.

(cherry picked from commit 0a76d635ca)

src/composer/http_client.py

@@ -93,7 +93,7 @@ def get_url_json(socket_path, url):
     r = http.request("GET", url)
     return json.loads(r.data.decode('utf-8'))
 
-def get_url_json_unlimited(socket_path, url):
+def get_url_json_unlimited(socket_path, url, total_fn=None):
     """Return the JSON results of a GET request
 
     For URLs that use offset/limit arguments, this command will
@@ -106,6 +106,10 @@ def get_url_json_unlimited(socket_path, url):
     :returns: The json response from the server
     :rtype: dict
     """
+    def default_total_fn(data):
+        """Return the total number of available results"""
+        return data["total"]
+
     http = UnixHTTPConnectionPool(socket_path)
 
     # Start with limit=0 to just get the number of objects
@@ -113,8 +117,12 @@ def get_url_json_unlimited(socket_path, url):
     r_total = http.request("GET", total_url)
     json_total = json.loads(r_total.data.decode('utf-8'))
 
+    # Where to get the total from
+    if not total_fn:
+        total_fn = default_total_fn
+
     # Add the "total" returned by limit=0 as the new limit
-    unlimited_url = append_query(url, "limit=%d" % json_total["total"])
+    unlimited_url = append_query(url, "limit=%d" % total_fn(json_total))
     r_unlimited = http.request("GET", unlimited_url)
     return json.loads(r_unlimited.data.decode('utf-8'))