Don't set repeat count to 0

app/src/main/java/com/todoroo/astrid/data/Task.kt

@@ -565,7 +565,7 @@ class Task : Parcelable {
         const val TRANS_REMINDERS = "reminders"
         const val TRANS_RANDOM = "random"
 
-        private val INVALID_COUNT = ";?COUNT=-1".toRegex()
+        private val INVALID_COUNT = ";?COUNT=(-1|0)".toRegex()
 
         /**
          * Creates due date for this task. If this due date has no time associated, we move it to the last

app/src/main/java/org/tasks/repeats/CustomRecurrenceDialog.java

@@ -463,7 +463,6 @@ public class CustomRecurrenceDialog extends DialogFragment {
     }
     if (position == 0) {
       rrule.setUntil(null);
-      rrule.setCount(0);
       updateRepeatUntilOptions();
     } else if (position == 1) {
       repeatUntilClick();

app/src/test/java/org/tasks/repeats/RecurrenceUtilsTest.kt

@@ -0,0 +1,22 @@
+package org.tasks.repeats
+
+import junit.framework.TestCase.assertEquals
+import org.junit.Test
+
+class RecurrenceUtilsTest {
+    @Test
+    fun shouldRemoveZeroCount() {
+        assertEquals(
+            "FREQ=WEEKLY;INTERVAL=1;BYDAY=FR",
+            RecurrenceUtils.newRecur("FREQ=WEEKLY;COUNT=0;INTERVAL=1;BYDAY=FR").toString()
+        )
+    }
+
+    @Test
+    fun shouldRemoveNegativeCount() {
+        assertEquals(
+            "FREQ=WEEKLY;INTERVAL=1;BYDAY=FR",
+            RecurrenceUtils.newRecur("FREQ=WEEKLY;COUNT=-1;INTERVAL=1;BYDAY=FR").toString()
+        )
+    }
+}