Fuzzing fails in concrete execution sometimes

[Markoutte]

Description

When only fuzzing is enabled there's a report about failed concrete execution for this code:

class A {
    public int f;
}

public class First {

    public void t(A a, A b) {
        a.f = 1;
        b.f = 2;

        if (a.f == b.f) {
            exp();
        }
    }

    private void exp() {
        throw new RuntimeException();
    }
}

To Reproduce

1. Enable only fuzzing
2. Run test generation for the example

Expected behavior

Generated only correct tests

Actual behavior

There's an information about failed concrete executions.

Visual proofs (screenshots, logs, images)

    public void testT_errors() {
        // Couldn't generate some tests. List of errors:
        // 
        // 7 occurrences of:
        // Default concrete execution failed

    }