Bugfix: only pass lefthand whitespace delta to _handle_indentation

[djangovanderheijden]

This fixes JUnit output in cases where the TAP file does not end with a trailing newline. It also improves behavior when tests are provided with an empty description which is technically allowed as per the TAP spec.

Take the following input file:

1..3
ok 1 Hello, world
ok 2 
ok 3 Hello, world

The resulting XML is as follows:

Before:

<?xml version="1.0" encoding="utf-8"?>
<testsuites disabled="0" errors="0" failures="2" tests="5" time="0.0">
	<testsuite disabled="0" errors="0" failures="2" name="..." skipped="0" tests="5" time="0" hostname="...">
		<testcase name="Hello, world"/>
		<testcase name="None">
			<failure type="failure" message=" (0)"/>
		</testcase>
		<testcase name="None"/>
		<testcase name="None">
			<failure type="failure" message=" (0)"/>
		</testcase>
		<testcase name="Hello, world"/>
	</testsuite>
</testsuites>

After:

<?xml version="1.0" encoding="utf-8"?>
<testsuites disabled="0" errors="0" failures="0" tests="3" time="0.0">
	<testsuite disabled="0" errors="0" failures="0" name="..." skipped="0" tests="3" time="0" hostname="...">
		<testcase name="Hello, world"/>
		<testcase name="None"/>
		<testcase name="Hello, world"/>
	</testsuite>
</testsuites>