gitview: Fix the graph display .

This fix all the known issue with the graph display
The bug need to be explained graphically

                                 |
                                 a
This line need not be there ---->| \
                                 b  |
                                 | /
                                 c

c is parent of a and all a,b and c are placed on the same line and b is child of c
With my last checkin I added  a seperate line to indicate that a is
connected to c. But then we had the line connecting a and b which should
not be ther. This changes fixes the same bug

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

contrib/gitview/gitview

@@ -938,8 +938,10 @@ class GitView:
 	def draw_incomplete_line(self, sha1, node_pos, out_line, in_line, index):
 		for idx, pos in enumerate(self.incomplete_line[sha1]):
 			if(pos == node_pos):
-				out_line.append((pos,
-					pos+0.5, self.colours[sha1]))
+				#remove the straight line and add a slash
+				if ((pos, pos, self.colours[sha1]) in out_line):
+					out_line.remove((pos, pos, self.colours[sha1]))
+				out_line.append((pos, pos+0.5, self.colours[sha1]))
 				self.incomplete_line[sha1][idx] = pos = pos+0.5
 			try:
 				next_commit = self.commits[index+1]