gnu: python-tinycss2: Fix test failure.

Fixes <https://bugs.gnu.org/42372>.
Reported by Michael Rohleder <mike@rohleder.de>.

* gnu/packages/patches/python-tinycss2-flake8-compat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/python-web.scm (python-tinycss2)[source](patches): New field.

gnu/local.mk

@@ -1466,6 +1466,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/python-shouldbe-0.1.2-cpy3.8.patch	\
   %D%/packages/patches/python-slugify-depend-on-unidecode.patch	\
   %D%/packages/patches/python2-subprocess32-disable-input-test.patch	\
+  %D%/packages/patches/python-tinycss2-flake8-compat.patch	\
   %D%/packages/patches/python-unittest2-python3-compat.patch	\
   %D%/packages/patches/python-unittest2-remove-argparse.patch	\
   %D%/packages/patches/python-waitress-fix-tests.patch		\

gnu/packages/patches/python-tinycss2-flake8-compat.patch

@@ -0,0 +1,36 @@
+Fix test failure that occurs with recent versions of Flake8.
+
+Taken from upstream:
+https://github.com/Kozea/tinycss2/commit/6556604fb98c2153412384d6f0f705db2da1aa60
+
+diff --git a/tinycss2/css-parsing-tests/make_color3_hsl.py b/tinycss2/css-parsing-tests/make_color3_hsl.py
+index d1fd3a6..56fda0c 100644
+--- a/tinycss2/css-parsing-tests/make_color3_hsl.py
++++ b/tinycss2/css-parsing-tests/make_color3_hsl.py
+@@ -8,16 +8,17 @@ def trim(s):
+ print('[')
+ print(',\n'.join(
+     '"hsl%s(%s, %s%%, %s%%%s)", [%s, %s, %s, %s]' % (
+-        ('a' if a is not None else '', h,
+-         trim(str(s / 10.)), trim(str(l / 10.)),
+-         ', %s' % a if a is not None else '') +
++        ('a' if alpha is not None else '', hue,
++         trim(str(saturation / 10.)), trim(str(light / 10.)),
++         ', %s' % alpha if alpha is not None else '') +
+         tuple(trim(str(round(v, 10)))
+-              for v in colorsys.hls_to_rgb(h / 360., l / 1000., s / 1000.)) +
+-        (a if a is not None else 1,)
++              for v in colorsys.hls_to_rgb(
++                hue / 360., light / 1000., saturation / 1000.)) +
++        (alpha if alpha is not None else 1,)
+     )
+-    for a in [None, 1, .2, 0]
+-    for l in range(0, 1001, 125)
+-    for s in range(0, 1001, 125)
+-    for h in range(0, 360, 30)
++    for alpha in [None, 1, .2, 0]
++    for light in range(0, 1001, 125)
++    for saturation in range(0, 1001, 125)
++    for hue in range(0, 360, 30)
+ ))
+ print(']')

gnu/packages/python-web.scm

@@ -3411,6 +3411,7 @@ library to create slugs from unicode strings while keeping it DRY.")
      (origin
        (method url-fetch)
        (uri (pypi-uri "tinycss2" version))
+       (patches (search-patches "python-tinycss2-flake8-compat.patch"))
        (sha256
         (base32 "1kw84y09lggji4krkc58jyhsfj31w8npwhznr7lf19d0zbix09v4"))))
     (build-system python-build-system)