[PATCH 2 of 2 py3] pycompat: custom implementation of urllib.parse.quote()

Gregory Szorc gregory.szorc at gmail.com
Mon Mar 13 15:27:23 EDT 2017

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1489432607 25200
#      Mon Mar 13 12:16:47 2017 -0700
# Node ID e6b177a3a7662366e8af0ba07ccbd9509a8cc647
# Parent  2b9547ebdfa84c3e96fd366e3c09dd24306747d4
pycompat: custom implementation of urllib.parse.quote()

urllib.parse.quote() accepts either str or bytes and returns str.

There exists a urllib.parse.quote_from_bytes() which only accepts
bytes. We should probably use that to retain strong typing and
avoid surprises.

In addition, since nearly all strings in Mercurial are bytes, we
probably don't want quote() returning unicode.

So, this patch implements a custom quote() that only accepts bytes
and returns bytes. The quoted URL should only contain URL safe
characters which is a strict subset of ASCII. So
`.encode('ascii', 'strict')` should be safe.

After this patch, `hg init <path>` works on Python 3.5!

diff --git a/mercurial/pycompat.py b/mercurial/pycompat.py
--- a/mercurial/pycompat.py
+++ b/mercurial/pycompat.py
@@ -269,7 +269,6 @@ if not ispy3:
     import urllib.parse
     urlreq._registeraliases(urllib.parse, (
-        "quote",
@@ -313,3 +312,12 @@ else:
+    # urllib.parse.quote() accepts both str and bytes, decodes bytes
+    # (if necessary), and returns str. This is wonky. We provide a custom
+    # implementation that only accepts bytes and emits bytes.
+    def quote(s, safe=r'/'):
+        s = urllib.parse.quote_from_bytes(s, safe=safe)
+        return s.encode('ascii', 'strict')
+    urlreq.quote = quote

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