build: get list of themes regardless of themes.json (#26857)

Makefile

@@ -22,7 +22,7 @@ themes.json: $(wildcard static/*/config.json)
 %.css: %.scss $(wildcard static/includes/*.scss) static/includes/_data_uris.scss static/grandlyon-gnm/_data_uris.scss static/toodego/_data_uris.scss $$(wildcard $$(@D)/*.scss)
 	sass $< $@
 
-css: $(wildcard static/*/style.css)
+css: $(shell python get_themes.py)
 	rm -rf static/*/.sass-cache/
 
 icons:
@@ -57,6 +57,7 @@ DIST_FILES = \
 	Makefile \
 	desc.xml \
 	create_themes_json.py \
+	get_themes.py \
 	make_data_uris.py \
 	static templates \
 	src

get_themes.py

@@ -0,0 +1,9 @@
+#! /usr/bin/env python
+
+import os
+
+for dirname in sorted(os.listdir('static')):
+    config = os.path.join('static', dirname, 'config.json')
+    if not os.path.exists(config):
+        continue
+    print 'static/%s/style.css' % dirname