Fix mime type info for converted images. Fixes #307

mautrix_telegram/portal.py

@@ -1386,7 +1386,11 @@ class Portal:
                 except ValueError:
                     name = alt
 
-        mime_type = document.mime_type or file.mime_type
+        generic_types = ("text/plain", "application/octet-stream")
+        if file.mime_type in generic_types and document.mime_type not in generic_types:
+            mime_type = document.mime_type or file.mime_type
+        else:
+            mime_type = file.mime_type or document.mime_type
         info = {
             "size": file.size,
             "mimetype": mime_type,

setup.py

@@ -31,7 +31,7 @@ setuptools.setup(
 
     install_requires=[
         "aiohttp>=3.0.1,<4",
-        "mautrix-appservice>=0.3.8,<0.4.0",
+        "mautrix-appservice>=0.3.9,<0.4.0",
         "SQLAlchemy>=1.2.3,<2",
         "alembic>=1.0.0,<2",
         "commonmark>=0.8.1,<1",