Disable emulation-attributes-bce on tmux 3.3a

tmux 3.3a has a behavior change, since reverted, that is incompatible
with this test. Unfortunately, tmux 3.3a has already made it into some
distributions, so the test has to be disabled when tmux 3.3a is encountered.

src/tests/e2e-test-subrs

@@ -81,6 +81,19 @@ set_locale()
     return 1
 }
 
+# Given two versions, return success if the first version is less than
+# or equal to the second version.
+versionlte()
+{
+    [  "$1" = "$(printf "$1\n$2\n" | sort -V | head -n1)" ]
+}
+versionlt() {
+    if [ "$1" = "$2" ]; then
+	return 1
+    fi
+    versionlte "$1" "$2"
+}
+
 # Tmux check.
 tmux_check()
 {
@@ -103,11 +116,8 @@ tmux_check()
 	return 0
     fi
     version=${version##tmux }
-    version_major=${version%%.*}
-    version_minor=${version##*.}
 
-    if [ "$version_major" -lt "$need_major" ] ||
-	{ [ "$version_major" -eq "$need_major" ] && [ "$version_minor" -lt "$need_minor" ]; }; then
+    if versionlt "$version" "$need_major.$need_minor"; then
 	printf "tmux version %s too old\n" "$version" >&2
 	return 1
     fi

src/tests/emulation-attributes.test

@@ -27,6 +27,14 @@ if [ "$(basename "$0")" = emulation-attributes-bce.test ] &&
     exit 77
 fi
 
+# tmux 3.3a has a behavior change in how BCE is handled, which has
+# been reverted: https://github.com/tmux/tmux/issues/3339
+if [ "$(basename "$0")" = emulation-attributes-bce.test ] &&
+   tmux_check 3 3a && ! tmux_check 3 3b; then
+    printf "tmux 3.3a has incompatible BCE behavior\n" >&2
+    exit 77
+fi
+
 # Top-level wrapper.
 if [ $# -eq 0 ]; then
     e2e-test "$0" baseline direct verify