Los síntomas:

Git se negó repentinamente a enviar un repositorio (a github en mi caso):

$ git push
Counting objects: 9292, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (2136/2136), done.
error: RPC failed; result=22, HTTP code = 411
fatal: The remote end hung up unexpectedly
Writing objects: 100% (8222/8222), 1.27 MiB | 837 KiB/s, done.
Total 8222 (delta 6060), reused 8181 (delta 6033)
fatal: The remote end hung up unexpectedly
Everything up-to-date