Merge pull request #15429 from ghalliday/issue26630

HPCC-26630 Avoid esp startup problem with dropzones with no instances

Reviewed-By: Jake Smith <jake.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>

dali/base/dafdesc.cpp

@@ -3186,7 +3186,12 @@ bool GroupInformation::checkIsSubset(const GroupInformation & other)
     //Find the first ip that matches, and then check the next ips within the other list also match
     unsigned thisSize = hosts.ordinality();
     unsigned otherSize = other.hosts.ordinality();
-    assertex(thisSize <= otherSize);
+    if (thisSize > otherSize)
+    {
+        if (dropZoneIndex)
+            return false;
+        throwUnexpected();
+    }
     for (unsigned i=0; i <= otherSize-thisSize; i++)
     {
         bool match = true;