Use Git diff drivers for Markdown and Python

[cffswb]

Please follow the guide below

• You will be asked some questions, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your pull request (like that [x])
• Use Preview tab to see how your pull request will actually look like

---

Before submitting a pull request make sure you have:

• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8

In order to be accepted and merged into yt-dlp each piece of code must be in public domain or released under Unlicense. Check one of the following options:

• I am the original author of this code and I am willing to release it under Unlicense
• I am not the original author of this code but it is in public domain or released under Unlicense (provide reliable evidence)

What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

---

Description of your pull request and other information

Git supports displaying more informative diffs for files with suitable diff drivers enabled. By using these diff drivers we can gain some more context on where the modifications are.

Example of Python without "python" diff driver:

diff --git a/yt_dlp/downloader/http.py b/yt_dlp/downloader/http.py
index 591a9b08d..a232168fa 100644
--- a/yt_dlp/downloader/http.py
+++ b/yt_dlp/downloader/http.py
@@ -145,7 +145,8 @@ class HttpFD(FileDownloader):
                             or content_len < range_end)
                         if accept_content_len:
                             ctx.content_len = content_len
-                            ctx.data_len = min(content_len, req_end or content_len) - (req_start or 0)
+                            if content_len or req_end:
+                                ctx.data_len = min(content_len or req_end, req_end or content_len) - (req_start or 0)
                             return
                     # Content-Range is either not present or invalid. Assuming remote webserver is
                     # trying to send the whole file, resume is not possible, so wiping the local file

With "python" diff driver:

diff --git a/yt_dlp/downloader/http.py b/yt_dlp/downloader/http.py
index 591a9b08d..a232168fa 100644
--- a/yt_dlp/downloader/http.py
+++ b/yt_dlp/downloader/http.py
@@ -145,7 +145,8 @@ def establish_connection():
                             or content_len < range_end)
                         if accept_content_len:
                             ctx.content_len = content_len
-                            ctx.data_len = min(content_len, req_end or content_len) - (req_start or 0)
+                            if content_len or req_end:
+                                ctx.data_len = min(content_len or req_end, req_end or content_len) - (req_start or 0)
                             return
                     # Content-Range is either not present or invalid. Assuming remote webserver is
                     # trying to send the whole file, resume is not possible, so wiping the local file

We can see the diff now shows def establish_connection(): instead of class HttpFD(FileDownloader): after the @@.

Example of Markdown without "markdown" diff driver:

diff --git a/README.md b/README.md
index 1aab0ba94..ce5af129e 100644
--- a/README.md
+++ b/README.md
@@ -737,9 +737,6 @@ You can also fork the project on github and run your fork's [build workflow](.gi
     --prefer-insecure                Use an unencrypted connection to retrieve
                                      information about the video (Currently
                                      supported only for YouTube)
-    --user-agent UA                  Specify a custom user agent
-    --referer URL                    Specify a custom referer, use if the video
-                                     access is restricted to one domain
     --add-header FIELD:VALUE         Specify a custom HTTP header and its value,
                                      separated by a colon ":". You can use this
                                      option multiple times
@@ -1866,6 +1863,8 @@ While these options are redundant, they are still expected to be used due to the
     --reject-title REGEX             --match-filter "title !~= (?i)REGEX"
     --min-views COUNT                --match-filter "view_count >=? COUNT"
     --max-views COUNT                --match-filter "view_count <=? COUNT"
+    --user-agent UA                  --add-header "User-Agent:UA"
+    --referer URL                    --add-header "Referer:URL"

With "markdown" diff driver (requires Git 2.27 or later):

diff --git a/README.md b/README.md
index 1aab0ba94..ce5af129e 100644
--- a/README.md
+++ b/README.md
@@ -737,9 +737,6 @@ ## Workarounds:
     --prefer-insecure                Use an unencrypted connection to retrieve
                                      information about the video (Currently
                                      supported only for YouTube)
-    --user-agent UA                  Specify a custom user agent
-    --referer URL                    Specify a custom referer, use if the video
-                                     access is restricted to one domain
     --add-header FIELD:VALUE         Specify a custom HTTP header and its value,
                                      separated by a colon ":". You can use this
                                      option multiple times
@@ -1866,6 +1863,8 @@ #### Redundant options
     --reject-title REGEX             --match-filter "title !~= (?i)REGEX"
     --min-views COUNT                --match-filter "view_count >=? COUNT"
     --max-views COUNT                --match-filter "view_count <=? COUNT"
+    --user-agent UA                  --add-header "User-Agent:UA"
+    --referer URL                    --add-header "Referer:URL"

[pukkandan]

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