t4010: abstract away SHA-1-specific constants

Adjust the test so that it computes variables for object IDs instead of
using hard-coded hashes.

Signed-off-by: brian m. carlson <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: bk2204

t/t4010-diff-pathspec.sh

@@ -17,11 +17,15 @@ test_expect_success \
     'echo frotz >file0 &&
      mkdir path1 &&
      echo rezrov >path1/file1 &&
+     before0=$(git hash-object file0) &&
+     before1=$(git hash-object path1/file1) &&
      git update-index --add file0 path1/file1 &&
      tree=$(git write-tree) &&
      echo "$tree" &&
      echo nitfol >file0 &&
      echo yomin >path1/file1 &&
+     after0=$(git hash-object file0) &&
+     after1=$(git hash-object path1/file1) &&
      git update-index file0 path1/file1'
 
 cat >expected <<\EOF
@@ -31,32 +35,32 @@ test_expect_success \
     'git diff-index --cached $tree -- path >current &&
      compare_diff_raw current expected'
 
-cat >expected <<\EOF
-:100644 100644 766498d93a4b06057a8e49d23f4068f1170ff38f 0a41e115ab61be0328a19b29f18cdcb49338d516 M	path1/file1
+cat >expected <<EOF
+:100644 100644 $before1 $after1 M	path1/file1
 EOF
 test_expect_success \
     'limit to path1 should show path1/file1' \
     'git diff-index --cached $tree -- path1 >current &&
      compare_diff_raw current expected'
 
-cat >expected <<\EOF
-:100644 100644 766498d93a4b06057a8e49d23f4068f1170ff38f 0a41e115ab61be0328a19b29f18cdcb49338d516 M	path1/file1
+cat >expected <<EOF
+:100644 100644 $before1 $after1 M	path1/file1
 EOF
 test_expect_success \
     'limit to path1/ should show path1/file1' \
     'git diff-index --cached $tree -- path1/ >current &&
      compare_diff_raw current expected'
 
-cat >expected <<\EOF
-:100644 100644 766498d93a4b06057a8e49d23f4068f1170ff38f 0a41e115ab61be0328a19b29f18cdcb49338d516 M	path1/file1
+cat >expected <<EOF
+:100644 100644 $before1 $after1 M	path1/file1
 EOF
 test_expect_success \
     '"*file1" should show path1/file1' \
     'git diff-index --cached $tree -- "*file1" >current &&
      compare_diff_raw current expected'
 
-cat >expected <<\EOF
-:100644 100644 8e4020bb5a8d8c873b25de15933e75cc0fc275df dca6b92303befc93086aa025d90a5facd7eb2812 M	file0
+cat >expected <<EOF
+:100644 100644 $before0 $after0 M	file0
 EOF
 test_expect_success \
     'limit to file0 should show file0' \