--- a/mercurial/cffi/mpatchbuild.py	Sat Oct 05 10:29:34 2019 -0400
+++ b/mercurial/cffi/mpatchbuild.py	Sun Oct 06 09:45:02 2019 -0400
@@ -4,12 +4,15 @@
 import os
 
 ffi = cffi.FFI()
-mpatch_c = os.path.join(os.path.join(os.path.dirname(__file__), '..',
-                                     'mpatch.c'))
+mpatch_c = os.path.join(
+    os.path.join(os.path.dirname(__file__), '..', 'mpatch.c')
+)
 with open(mpatch_c) as f:
-    ffi.set_source("mercurial.cffi._mpatch", f.read(),
-                   include_dirs=["mercurial"])
-ffi.cdef("""
+    ffi.set_source(
+        "mercurial.cffi._mpatch", f.read(), include_dirs=["mercurial"]
+    )
+ffi.cdef(
+    """
 
 struct mpatch_frag {
        int start, end, len;
@@ -30,7 +33,8 @@
 struct mpatch_flist *mpatch_fold(void *bins,
                        struct mpatch_flist* (*get_next_item)(void*, ssize_t),
                        ssize_t start, ssize_t end);
-""")
+"""
+)
 
 if __name__ == '__main__':
     ffi.compile()