Markdown writer: changes to `--reference-links`.

With `--reference-location` of `section` or `block`, pandoc
will now repeat references that have been used in earlier
sections.

The Markdown reader has also been modified, so that *exactly*
repeated references do not generate a warning, only
references with the same label but different targets.

The idea is that, with references after every block,
one  might want to repeat references sometimes.

Closes #3701.

1 files changed, 60 insertions, 0 deletions

diff --git a/test/command/3701.md b/test/command/3701.md
new file mode 100644
index 000000000..01e438639
--- /dev/null
+++ b/test/command/3701.md
@@ -0,0 +1,60 @@
+```
+% pandoc --reference-location=block -t markdown --reference-links --wrap=preserve
+[a](u)
+
+[a](u)
+
+[a](u2)
+[A](u)
+[a](u){.foo}
+
+[a](u3)
+^D
+[a]
+
+  [a]: u
+
+[a]
+
+  [a]: u
+
+[a][1]
+[A][]
+[a][2]
+
+  [1]: u2
+  [A]: u
+  [2]: u {.foo}
+
+[a][3]
+
+  [3]: u3
+```
+
+```
+% pandoc
+[a]
+
+  [a]: u
+
+[a]
+
+  [a]: u
+
+[a][1]
+[A][]
+[a][2]
+
+  [1]: u2
+  [A]: u
+  [2]: u {.foo}
+
+[a][3]
+
+  [3]: u3
+^D
+<p><a href="u">a</a></p>
+<p><a href="u">a</a></p>
+<p><a href="u2">a</a> <a href="u">A</a> <a href="u" class="foo">a</a></p>
+<p><a href="u3">a</a></p>
+```