When $TMPDIR is low on space PHP streams silently fail

src/Composer/Util/RemoteFilesystem.php

@@ -179,6 +179,10 @@ class RemoteFilesystem
                     // work around issue with gzuncompress & co that do not work with all gzip checksums
                     $result = file_get_contents('compress.zlib://data:application/octet-stream;base64,'.base64_encode($result));
                 }
+
+                if (!$result) {
+                    throw new TransportException('Failed to decode zlib stream');
+                }
             }
         }