meta:hooks:pre-push: Adjust to more concise style

Adjust the sample code from git to a more concise coding style, placing
{do,then} on the same line and using `[` instead of `test`.

meta/git/hooks/pre-push

@@ -26,15 +26,12 @@ url="$2"
 
 zero=$(git hash-object --stdin </dev/null | tr '[0-9a-f]' '0')
 
-while read local_ref local_oid remote_ref remote_oid
-do
-	if test "$local_oid" = "$zero"
-	then
+while read local_ref local_oid remote_ref remote_oid; do
+	if [ "$local_oid" = "$zero" ]; then
 		# Handle delete
 		:
 	else
-		if test "$remote_oid" = "$zero"
-		then
+		if [ "$remote_oid" = "$zero" ]; then
 			# New branch, examine all commits
 			range="$local_oid"
 		else
@@ -46,8 +43,7 @@ do
 		pattern='^(WIP|(fixup|squash)!)'
 
 		commits="$(git rev-list -E --oneline --grep "$pattern" "$range")"
-		if test -n "$commits"
-		then
+		if [ -n "$commits" ]; then
 			printf >&2 "$local_ref: Commits in progress:\n%s" "$commits"
 			printf >&2 "Aborting push"
 			exit 1