Don't fail when a message uses a weird charset

Found via auto-testing in:
https://lore.kernel.org/linux-sgx/20200421215316.56503-13-jarkko.sakkinen@linux.intel.com/raw

This is wrong on many levels:
    Content-Type: text/plain; charset=a

Assume utf-8 when something like this happens and don't fail.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/b4/__init__.py b/b4/__init__.py
index ad417e6..2e12b60 100644
--- a/b4/__init__.py
+++ b/b4/__init__.py
@@ -682,7 +682,13 @@ class LoreMessage:
             pcharset = part.get_content_charset()
             if not pcharset:
                 pcharset = mcharset
-            payload = payload.decode(pcharset, errors='replace')
+            try:
+                payload = payload.decode(pcharset, errors='replace')
+            except LookupError:
+                # what kind of encoding is that?
+                # Whatever, we'll use utf-8 and hope for the best
+                payload = payload.decode('utf-8', errors='replace')
+                part.set_param('charset', 'utf-8')
             if self.body is None:
                 self.body = payload
                 continue