Update comment and error message if flushing pipe fails

Signed-off-by: John Eckersberg <[email protected]>

Author: jeckersb

ostree-ext/src/generic_decompress.rs

@@ -94,13 +94,17 @@ impl Drop for Decompressor {
             return;
         }
 
-        // We really should not get here; users are required to call
-        // `finish()` to clean up the stream.  But we'll give
+        // Ideally we should not get here; users should call
+        // `finish()` to clean up the stream.  But in reality there's
+        // codepaths that can and will short-circuit error out while
+        // processing the stream, and the Decompressor will get
+        // dropped before it's finished in those cases.  We'll give
         // best-effort to clean things up nonetheless.  If things go
         // wrong, then panic, because we're in a bad state and it's
         // likely that we end up with a broken pipe error or a
         // deadlock.
-        self._finish().expect("Decompressor::finish MUST be called")
+        self._finish()
+            .expect("Failed to flush pipe while dropping Decompressor")
     }
 }