BitSet: truncation in or_and

For "this |= set1 & set2" the result size
should be "max(this, min(set1, set2))" while
at present it is "min(set1, set2)" resulting
in truncation if the LHS is longer than the
RHS.
(cherry picked from commit d4292d81f2)

Number of tests planned corrected.

src/misc/bitSet.cpp

@@ -279,7 +279,8 @@ namespace epics { namespace pvData {
         uint32 inUse = (set1.wordsInUse < set2.wordsInUse) ? set1.wordsInUse : set2.wordsInUse;
 
         ensureCapacity(inUse);
-        wordsInUse = inUse;
+        if(inUse>wordsInUse)
+            wordsInUse = inUse;
 
         // Perform logical AND on words in common
         for (uint32 i = 0; i < inUse; i++)

testApp/misc/testBitSet.cpp

@@ -146,12 +146,19 @@ static void testOperators()
     b1.or_and(b2, b3);
     str = toString(b1);
     testOk1(str == "{2, 128}");
+
+    b1.clear(); b1.set(1);
+    b2.clear();
+    b3.clear(); b3.set(1);
+    std::cout<<"# "<<toString(b3)<<" |= "<<toString(b1)<<" & "<<toString(b2)<<"\n";
+    b3.or_and(b1, b2);
+    testOk(toString(b3) == "{1}", "%s == {1}", toString(b3).c_str());
 }
 
 
 MAIN(testBitSet)
 {
-    testPlan(29);
+    testPlan(30);
     testGetSetClearFlip();
     testOperators();
     return testDone();