Latest pijul and linux2x, run ./fork-unrec.sh:

$ cat /tmp/report-a99145b3-6792-4acc-8e7d-7d3c1d84135a.toml
name = 'pijul'
operating_system = 'unix:Manjaro'
crate_version = '1.0.0-alpha.48'
explanation = '''
Panic occurred in file '/home/mpech/pijul/libpijul/src/unrecord/mod.rs' at line 69
'''
cause = 'assertion failed: txn.get_revdep(&change_id, None)?.is_none()'
method = 'Panic'
backtrace = '''

   0: 0x58a46503ab7d - core::panicking::panic::h2d79ca19ff17340e
                at /build/rust/src/rustc-1.50.0-src/library/core/src/panicking.rs:50
   1: 0x58a46494d309 - libpijul::unrecord::unrecord::hc702b600eff07ed6
   2: 0x58a464ae50e1 - pijul::run::{{closure}}::h9fe33594579a140c
   3: 0x58a464a8fdfb - <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h300db49d1d06bae2
   4: 0x58a4649c3ee4 - tokio::runtime::thread_pool::ThreadPool::block_on::hdcebc6ebb12d8fa9
   5: 0x58a464aff09e - tokio::runtime::Runtime::block_on::hdb366f1a730c944a
   6: 0x58a464a1ff36 - pijul::main::h69da34b14e0b5874
   7: 0x58a46498d553 - std::sys_common::backtrace::__rust_begin_short_backtrace::h1746ba58e3ec5bb1
   8: 0x58a46490ef09 - std::rt::lang_start::{{closure}}::h154d7273c224f478
   9: 0x58a465019db7 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::h5a27e92186d531b9
                at /build/rust/src/rustc-1.50.0-src/library/core/src/ops/function.rs:259
                 - std::panicking::try::do_call::h8d3a36b2860fc4e2
                at /build/rust/src/rustc-1.50.0-src/library/std/src/panicking.rs:379
                 - std::panicking::try::hefdcf6df93f20790
                at /build/rust/src/rustc-1.50.0-src/library/std/src/panicking.rs:343
                 - std::panic::catch_unwind::h36ddc1c42bb74870
                at /build/rust/src/rustc-1.50.0-src/library/std/src/panic.rs:396
                 - std::rt::lang_start_internal::ha6cc4bb09c664b1a
                at /build/rust/src/rustc-1.50.0-src/library/std/src/rt.rs:51
  10: 0x58a464a1fff2 - main
  11: 0xfb59206bb25 - __libc_start_main
  12: 0x58a4648f227e - _start
  13:        0x0 - <unresolved>'''
$

Thanks! The dependencies and reverse dependencies of the change were not cleaned up in the call to pijul chann delete m1, when the second change stops being used in any channel.