fix: handle tags in nested blockquotes

pulldown-cmark/specs/blockquotes_tags.txt

@@ -103,3 +103,13 @@ And consecutive blockquotes too:
 .
 <blockquote class="markdown-alert-caution"><p>Line 1.</p></blockquote><blockquote class="markdown-alert-tip"><p>Line 2.</p></blockquote>
 ````````````````````````````````
+
+Tags also work in inner blockquotes:
+```````````````````````````````` example
+> > [!CAUTION]
+> > Line 1.
+> Line 2.
+.
+<blockquote><blockquote class="markdown-alert-caution"><p>Line 1.
+Line 2.</p></blockquote></blockquote>
+````````````````````````````````

pulldown-cmark/src/scanners.rs

@@ -209,8 +209,8 @@ impl<'a> LineStart<'a> {
                         self.ix += scan_nextline(&self.bytes[self.ix..]);
                         // Go to the next line of the blockquote if any
                         // omitting the '> ' to not create a nested blockquote
-                        if self.scan_ch(b'>') {
-                            let _ = self.scan_space(1);
+                        while self.scan_ch(b'>') {
+                            self.scan_space(1);
                         }
                     }
                     match tag {

pulldown-cmark/tests/suite/blockquotes_tags.rs

@@ -133,3 +133,16 @@ fn blockquotes_tags_test_11() {
 
     test_markdown_html(original, expected, false, false, false);
 }
+
+#[test]
+fn blockquotes_tags_test_12() {
+    let original = r##"> > [!CAUTION]
+> > Line 1.
+> Line 2.
+"##;
+    let expected = r##"<blockquote><blockquote class="markdown-alert-caution"><p>Line 1.
+Line 2.</p></blockquote></blockquote>
+"##;
+
+    test_markdown_html(original, expected, false, false, false);
+}