[FIX] match all occurrences of static/attach

If a markup element contains more than one {static} or {attach} value,
only the last one was replaced.

Simplify the regex to match every occurrence

Fixes getpelican/pelican#3419

pelican/contents.py

@@ -372,9 +372,7 @@ class Content:
     def _get_intrasite_link_regex(self) -> re.Pattern:
         intrasite_link_regex = self.settings["INTRASITE_LINK_REGEX"]
         regex = rf"""
-            (?P<markup><[^\>]+  # match tag with all url-value attributes
-                (?:href|src|poster|data|cite|formaction|action|content)\s*=\s*)
-
+            (?P<markup>(?:href|src|poster|data|cite|formaction|action|content)\s*=\s*)
             (?P<quote>["\'])      # require value to be quoted
             (?P<path>{intrasite_link_regex}(?P<value>.*?))  # the url value
             (?P=quote)"""

pelican/tests/test_contents.py

@@ -519,6 +519,9 @@ class TestPage(TestBase):
             "images/poster.jpg": Static(
                 "", settings=args["settings"], source_path="images/poster.jpg"
             ),
+            "images/placeholder.jpg": Static(
+                "", settings=args["settings"], source_path="images/placeholder.jpg"
+            ),
         }
         args["context"]["generated_content"] = {
             "article.rst": Article(
@@ -547,6 +550,16 @@ class TestPage(TestBase):
             content, '<img src="http://static.cool.site/images/poster.jpg"/>'
         )
 
+        # Image with two links
+        args["content"] = (
+            '<img src="{static}/images/placeholder.jpg" data-src="{static}/images/poster.jpg"/>'
+        )
+        content = Page(**args).get_content("http://cool.site")
+        self.assertEqual(
+            content,
+            '<img src="http://static.cool.site/images/placeholder.jpg" data-src="http://static.cool.site/images/poster.jpg"/>',
+        )
+
         # Image link will go to static
         args["content"] = '<meta content="{static}/images/poster.jpg"/>'
         content = Page(**args).get_content("http://cool.site")