Respect user-input legend facecolor (fixes #402)

Author: lukelbd

WHATSNEW.rst

@@ -247,6 +247,8 @@ Bug fixes
   `~proplot.colors.DiscreteColormap` incorrectly samples the color list (:issue:`299`).
 * Fix issue where `~proplot.axes.Axes.legend` ignores the user-input `fontsize`
   (:issue:`331`).
+* Fix issue where `~proplot.axes.Axes.legend` ignores the user-input `facecolor`
+  but not the shorthand `fc` (:issue:`402`).
 * Fix issue where passing invalid rc setting to ``.format`` results in persistent
   invalid `rc` state requiring restarting the session/configurator (:issue:`348`).
 * Fix issue where ``proplotrc`` settings are ignored if a subsequent line contains

proplot/axes/base.py

@@ -1605,7 +1605,7 @@ def _parse_frame(guide, fancybox=None, shadow=None, **kwargs):
         kw_frame = _pop_kwargs(
             kwargs,
             alpha=('a', 'framealpha', 'facealpha'),
-            facecolor=('fc', 'framecolor', 'facecolor'),
+            facecolor=('fc', 'framecolor'),
             edgecolor=('ec',),
             edgewidth=('ew',),
         )

proplot/internals/__init__.py

@@ -269,6 +269,7 @@ def _pop_kwargs(kwargs, *keys, **aliases):
     aliases.update({key: () for key in keys})
     for key, aliases in aliases.items():
         aliases = (aliases,) if isinstance(aliases, str) else aliases
+        aliases = tuple(alias for alias in aliases if alias != key)  # prevent dev errs
         opts = {key: kwargs.pop(key, None) for key in (key, *aliases)}
         value = _not_none(**opts)
         if value is not None: