Incorrect handling of QString arg values combined with missing markers

When using a string with arg markers (%1, %2 etc) and there is missing markers (ex: only %2) QString will incorrectly use the first arg instead of the second. For example,

qDebug() << QString("Test-D %2").arg("foo").arg("bar")

qDebug() << QString("Test-H %3 %3 %3").arg("foo").arg("bar")

Will output "Test-D foo" instead of "Test-D bar" and "Test-H foo foo foo" instead of "Test-H %3 %3 %3"

More complete list of working/not working examples follow:

Test case #1: qDebug() << QString("Test-A %1 %2").arg("foo").arg("bar")
Correct and expected output: Test-A foo bar

Test case #2: qDebug() << QString("Test-B %2 %1").arg("foo").arg("bar")
Correct and expected output: Test-B bar foo

Test case #3: qDebug() << QString("Test-C %1").arg("foo").arg("bar")
Correct and expected output: Test-C foo
Diag message: QString::arg: Argument missing: Test-C foo, bar

Test case #4: qDebug() << QString("Test-D %2").arg("foo").arg("bar")
Expected Output: Test-D bar
Incorrect output: Test-D foo
Diag message: QString::arg: Argument missing: Test-D foo, bar

Test case #5: qDebug() << QString("Test-E %3").arg("foo").arg("bar")
Expected Output: Test-E
Incorrect output: Test-E foo
Diag message: QString::arg: Argument missing: Test-E foo, bar

Test case #6: qDebug() << QString("Test-F %1 %2 %3").arg("foo").arg("bar")
Correct and expected output: Test-F foo bar %3

Test case #7: qDebug() << QString("Test-G %3 %1 %2").arg("foo").arg("bar")
Correct and expected output: Test-G %3 foo bar

Test case #8: qDebug() << QString("Test-H %3 %3 %3").arg("foo").arg("bar")
Expected output: Test-H %3 %3 %3
Incorrect output: Test-H foo foo foo
Diag message: QString::arg: Argument missing: Test-H foo foo foo, bar