From 4b16d181e7219ed161a0e03c0c5ee9dec4b526b4 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Thu, 27 May 2021 14:16:37 -0700
Subject: [PATCH] rebase_relative_paths: leave empty paths unchanged.

---
 MANUAL.txt                          | 4 ++--
 src/Text/Pandoc/Readers/Markdown.hs | 2 +-
 test/command/3752.md                | 3 +++
 test/command/chap1/text.md          | 2 ++
 4 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/MANUAL.txt b/MANUAL.txt
index fb1a76e9a..c234debc9 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -5081,8 +5081,8 @@ Without this extension, you would have to use
 `![image](chap2/spider.jpg)` in `chap2/text.md`.  Links with
 relative paths will be rewritten in the same way as images.
 
-Absolute paths and URLs are not changed.  Neither are paths
-consisting entirely of a fragment, e.g. `[section one](#foo)`.
+Absolute paths and URLs are not changed.  Neither are empty
+paths or paths consisting entirely of a fragment, e.g., `#foo`.
 
 Note that relative paths in reference links and images will
 be rewritten relative to the file containing the link
diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index 74f2668e4..bc5e3e30f 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/src/Text/Pandoc/Readers/Markdown.hs
@@ -1924,7 +1924,7 @@ rebasePath :: SourcePos -> Text -> Text
 rebasePath pos path = do
   let fp = sourceName pos
       isFragment = T.take 1 path == "#"
-   in if isFragment || isAbsolute (T.unpack path) || isURI path
+   in if T.null path || isFragment || isAbsolute (T.unpack path) || isURI path
          then path
          else
            case takeDirectory fp of
diff --git a/test/command/3752.md b/test/command/3752.md
index 2765d79ac..df8af0ba1 100644
--- a/test/command/3752.md
+++ b/test/command/3752.md
@@ -20,6 +20,8 @@ Absolute path left alone: absolute.
 
 Link to fragment: chapter two.
 
+Empty path: empty.
+
 Chapter two
 
 A spider: [spider]
@@ -36,6 +38,7 @@ A spider: [spider]
 <p>URL left alone: <a href="https://pandoc.org/MANUAL.html">manual</a>.</p>
 <p>Absolute path left alone: <a href="/foo/bar/baz.png">absolute</a>.</p>
 <p>Link to fragment: <a href="#chapter-two">chapter two</a>.</p>
+<p>Empty path: <a href="">empty</a>.</p>
 <h1 id="chapter-two">Chapter two</h1>
 <p>A spider: <img src="command/chap2/spider.png" alt="spider" /></p>
 ```
diff --git a/test/command/chap1/text.md b/test/command/chap1/text.md
index 68a317161..54f0104de 100644
--- a/test/command/chap1/text.md
+++ b/test/command/chap1/text.md
@@ -13,3 +13,5 @@ URL left alone: [manual](https://pandoc.org/MANUAL.html).
 Absolute path left alone: [absolute](/foo/bar/baz.png).
 
 Link to fragment: [chapter two](#chapter-two).
+
+Empty path: [empty]().