Reduce value duplication in t9300-fast-import.

It is error prone to list the value of each file twice, instead we
should list the value only once early in the script and reuse the
shell variable when we need to access it.
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>

t/t9300-fast-import.sh

@@ -7,6 +7,16 @@ test_description='test git-fast-import utility'
 . ./test-lib.sh
 . ../diff-lib.sh ;# test-lib chdir's into trash
 
+file2_data='file2
+second line of EOF'
+
+file3_data='EOF
+in 3rd file
+ END'
+
+file4_data=abcd
+file4_len=4
+
 ###
 ### series A
 ###
@@ -16,22 +26,19 @@ cat >input <<INPUT_END
 blob
 mark :2
 data <<EOF
-file2
-second line of EOF
+$file2_data
 EOF
 
 blob
 mark :3
 data <<END
-EOF
-in 3rd file
- END
+$file3_data
 END
 
 blob
 mark :4
-data 4
-abcd
+data $file4_len
+$file4_data
 commit refs/heads/master
 mark :5
 committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
@@ -73,24 +80,17 @@ test_expect_success \
 	'git-cat-file -p master^{tree} | sed "s/ [0-9a-f]*	/ /" >actual &&
 	 diff -u expect actual'
 
-cat >expect <<EOF
-file2
-second line of EOF
-EOF
+echo "$file2_data" >expect
 test_expect_success \
 	'A: verify file2' \
 	'git-cat-file blob master:file2 >actual && diff -u expect actual'
 
-cat >expect <<END
-EOF
-in 3rd file
- END
-END
+echo "$file3_data" >expect
 test_expect_success \
 	'A: verify file3' \
 	'git-cat-file blob master:file3 >actual && diff -u expect actual'
 
-printf abcd >expect
+printf "$file4_data" >expect
 test_expect_success \
 	'A: verify file4' \
 	'git-cat-file blob master:file4 >actual && diff -u expect actual'