ported missing sequence updates from 1.9

lib/ansible/plugins/lookup/sequence.py

@@ -152,15 +152,26 @@ class LookupModule(LookupBase):
             )
         elif self.count is not None:
             # convert count to end
+            if self.count != 0:
                 self.end = self.start + self.count * self.stride - 1
+            else:
+                self.start = 0
+                self.end = 0
+                self.stride = 0
             del self.count
-        if self.end < self.start:
-            raise AnsibleError("can't count backwards")
+        if self.stride > 0 and self.end < self.start:
+            raise AnsibleError("to count backwards make stride negative")
+        if self.stride < 0 and self.end > self.start:
+            raise AnsibleError("to count forward don't make stride negative")
         if self.format.count('%') != 1:
             raise AnsibleError("bad formatting string: %s" % self.format)
 
     def generate_sequence(self):
-        numbers = xrange(self.start, self.end + 1, self.stride)
+        if self.stride > 0:
+            adjust = 1
+        else:
+            adjust = -1
+        numbers = xrange(self.start, self.end + adjust, self.stride)
 
         for i in numbers:
             try:
@@ -191,13 +202,13 @@ class LookupModule(LookupBase):
                     raise AnsibleError("unknown error parsing with_sequence arguments: %r. Error was: %s" % (term, e))
 
                 self.sanity_check()
-
+                if self.stride != 0:
                     results.extend(self.generate_sequence())
             except AnsibleError:
                 raise
-            except Exception:
+            except Exception as e:
                 raise AnsibleError(
-                    "unknown error generating sequence"
+                    "unknown error generating sequence: %s" % e
                 )
 
         return results

test/integration/roles/test_iterators/tasks/main.yml

@@ -81,10 +81,15 @@
   with_sequence: count=0
   register: count_of_zero
 
+- name: test with_sequence count 1
+  set_fact: "{{ 'x' + item }}={{ item }}"
+  with_sequence: count=1
+  register: count_of_one
+
 - assert:
     that:
         - count_of_zero | skipped
-        - not count_of_zero | failed
+        - not count_of_one | skipped
 
 # WITH_RANDOM_CHOICE