global: replace references to 'sha1' with 'oid'

For some time now sha1 is considered broken and upstream is working to
replace it with sha256. Replace all references to 'sha1' with 'oid',
just as upstream does.

Signed-off-by: Christian Hesse <mail@eworm.de>

tests/t0001-validate-git-versions.sh

@@ -33,10 +33,10 @@ test_expect_success 'test submodule version matches Makefile' '
 	else
 		(
 			cd ../.. &&
-			sm_sha1=$(git ls-files --stage -- git |
+			sm_oid=$(git ls-files --stage -- git |
 				sed -e "s/^[0-9]* \\([0-9a-f]*\\) [0-9]	.*$/\\1/") &&
 			cd git &&
-			git describe --match "v[0-9]*" $sm_sha1
+			git describe --match "v[0-9]*" $sm_oid
 		) | sed -e "s/^v//" -e "s/-/./" >sm_version &&
 		test_cmp sm_version makefile_version
 	fi