maint: fix git hooks logic error

`test set = set = set` is invalid, as is `test set = = set`.
Tweak the code to what was probably intended.

* build-aux/git-hooks/commit-msg: Fix $ECHO test call.

diff --git a/build-aux/git-hooks/commit-msg b/build-aux/git-hooks/commit-msg
index c675661b36f51608b20de14612e843350151a260..dc70a69f70ce1887666cb1856d865906e2a4de7f 100755 (executable)
--- a/build-aux/git-hooks/commit-msg
+++ b/build-aux/git-hooks/commit-msg
@@ -23,7 +23,7 @@
 
 
 : ${SED="sed"}
-test set = ${ECHO+'set'} = set || ECHO='printf %s\n'
+test "${ECHO+set}" = set || ECHO='printf %s\n'
 
 basename='s|^.*/||'