feat(jungle): add fallback 3rd-party completion loader

https://github.com/achiku/jungle
https://github.com/achiku/jungle/blob/fb63f845cfa9e9c0dfbabd8cfa3ebca8177a11ca/README.md#autocompletion-currently-only-supports-bash
https://github.com/ohmybash/oh-my-bash/blob/b4a2264496e14f883101ec15e35607b2e7386acc/completions/jungle.completion.sh

completions/Makefile.am

@@ -208,6 +208,7 @@ bashcomp_DATA = 2to3 \
 		jshint \
 		json_xs \
 		jsonschema \
+		_jungle \
 		k3b \
 		kcov \
 		_keyring \

completions/_jungle

@@ -0,0 +1,16 @@
+# 3rd party completion loader for commands emitting        -*- shell-script -*-
+# their completion using "_${cmdname^^}_COMPLETE=source $cmd".
+# This pattern is very similar to `completions/_pipenv`, but the value of the
+# environment variable is slightly different.
+#
+# This serves as a fallback in case the completion is not installed otherwise.
+
+eval -- "$(
+    # shellcheck disable=SC2154
+    ucname="${cmdname^^}"
+    ucname=${ucname//-/_}
+    export "_${ucname}_COMPLETE=source"
+    "$1" 2>/dev/null
+)"
+
+# ex: filetype=sh

test/fallback/completions/Makefile.am

@@ -14,6 +14,7 @@ EXTRA_DIST = \
 	hexdump \
 	hwclock \
 	ionice \
+	jungle \
 	keyring \
 	kontena \
 	look \

test/fallback/completions/jungle

@@ -0,0 +1 @@
+../../../completions/_jungle