`Patch.changed_lines` method's numbering falsely includes lines like `\ No newline at end of file`

[radomirbosak]

This has a side-effect that line numbers are shifted by +1 if the patch is near end of the file which does not have a trailing newline.

How to reproduce

If we have this unified diff:

diff --git a/file.txt b/file.txt
index 2ae21dc..0ce0636 100644
--- a/file.txt
+++ b/file.txt
@@ -1,2 +1 @@
-First
\ No newline at end of file
+Second

And we inspect the changed_lines of this patch:

require "git_diff_parser"

output = File.open("file.diff").read

patches = GitDiffParser.parse(output)
puts patches[0].changed_lines.inspect

We will get this output

[#<GitDiffParser::Line:0x00005602fda5fd88 @number=2, @content="+Second\n", @patch_position=3>]

Expectation:

@number=1

Reality:

@number=2

[sanemat]

good catch!

[radomirbosak]

#336 should fix this, please take a look.