tests/test_git: Fix test failure on FreeBSD

Closes: #872826
Thanks: Ximin Luo <infinity0@debian.org> for the initial patch
Signed-off-by: Mattia Rizzolo <mattia@debian.org>

tests/comparators/test_git.py

@@ -19,6 +19,7 @@
 
 import pytest
 
+from diffoscope.tools import get_current_os
 from diffoscope.comparators.git import GitIndexFile
 
 from ..utils.data import get_data, load_fixture
@@ -42,5 +43,8 @@ def differences(git1, git2):
 
 
 def test_diff(differences):
-    expected_diff = get_data('git_expected_diff')
+    if get_current_os == 'FreeBSD':
+        expected_diff = get_data('git_expected_diff_freebsd')
+    else:
+        expected_diff = get_data('git_expected_diff')
     assert differences[0].unified_diff == expected_diff

tests/data/git_expected_diff_freebsd

+@@ -10,7 +10,18 @@
+ User ID:   1000
+ Group ID:  1000
+ Created:   1471689380.154572964
+ Modified:  1471689380.154572964
+ Inode:     52205983
+ Device ID: (0, 2054)
+ 
++Path:      b'b'
++SHA:       e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
++Size:      0
++Flags:     0b1
++User ID:   1000
++Group ID:  1000
++Created:   1471689417.184218147
++Modified:  1471689417.184218147
++Inode:     52206041
++Device ID: (0, 2054)
++