ConvertUsfmVersificationHandler doesn't merge verses correctly

[pmachapman]

The English versification has the following verse mapping for Psalm 51 which merges two verses into one:

PSA 51:0 = PSA 51:1
PSA 51:0 = PSA 51:2
PSA 51:1-19 = PSA 51:3-21

When converting Psalm 51 from Original to English Versification, the following USFM is generated:

\id PSA
\c 51
\s1 Create in Me a Clean Heart, O God
\r (2 Samuel 12:1–12)
\p
\v 0 For the choirmaster. A Psalm of David.
\v 0 When Nathan the prophet came to him after his adultery with Bathsheba.
\b
\q1
\v 1 Have mercy on me,\f + \fr 51:3 \ft Or \fqa Be gracious to me\f* O God,
\q2 according to Your loving devotion;
\q1 according to Your great compassion,
\q2 blot out my transgressions.
...

A test which recreates this scenario:

[Test]
public void GetUsfm_MergedVerses()
{
	// Original vs. English
	// PSA 51:1-3 = PSA 51:0-1

	string usfm =
		@"\id PSA
\c 51
\s1 Create in Me a Clean Heart, O God
\r (2 Samuel 12:1–12)
\p
\v 1 For the choirmaster. A Psalm of David.
\v 2 When Nathan the prophet came to him after his adultery with Bathsheba.
\b
\q1
\v 3 Have mercy on me,\f + \fr 51:3 \ft Or \fqa Be gracious to me\f* O God,
\q2 according to Your loving devotion;
\q1 according to Your great compassion,
\q2 blot out my transgressions.
";

	string target = UpdateUsfm(usfm, sourceVersification: ScrVers.Original, targetVersification: ScrVers.English);
	string result =
		@"\id PSA
\c 51
\s1 Create in Me a Clean Heart, O God
\r (2 Samuel 12:1–12)
\p
\v 0 For the choirmaster. A Psalm of David. When Nathan the prophet came to him after his adultery with Bathsheba.
\b
\q1 \v 1 Have mercy on me,\f + \fr 51:1 \ft Or \fqa Be gracious to me\f* O God,
\q2 according to Your loving devotion;
\q1 according to Your great compassion,
\q2 blot out my transgressions.
";
	AssertUsfmEquals(target, result);
}