test: random failure

[tac0turtle]

Summary

Debug failing test:

 pool_test.go:129: ___ response: 0x72
    pool_test.go:137: 
        	Error Trace:	pool_test.go:137
        	Error:      	Not equal: 
        	            	expected: 500
        	            	actual  : 8
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -3,3 +3,3 @@
        	            	  abs: (big.nat) (len=1) {
        	            	-  (big.Word) 500
        	            	+  (big.Word) 8
        	            	  }
        	Test:       	TestTotalBatchFeeInPool
    pool_test.go:138: 
        	Error Trace:	pool_test.go:138
        	Error:      	Not equal: 
        	            	expected: 8
        	            	actual  : 500
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -3,3 +3,3 @@
        	            	  abs: (big.nat) (len=1) {
        	            	-  (big.Word) 8
        	            	+  (big.Word) 500
        	            	  }
        	Test:       	TestTotalBatchFeeInPool
FAIL

If we cant reproduce we can close.