Rustc panics if an incremental file is gzipped

[jyn514]

Code

$ cargo new gz-ice && cd gz-ice
$ cargo build
$ find target -type f -exec gzip {} \;
$ cargo run
thread 'rustc' panicked at 'src/librustc_incremental/persist/fs.rs:569: unexpected incr-comp session dir: /home/joshua/src/rust/gz-ice/target/debug/incremental/gz_ice-1ozj25zbd5kq1/s-fmyyvvfq9d-5g7yck.lock.gz', src/librustc_middle/util/bug.rs:37:26
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.44.0-nightly (7f3df5772 2020-04-16) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental -C link-arg=-fuse-ld=lld --crate-type bin

note: some of the compiler flags provided by cargo are hidden

Meta

rustc --version --verbose:

rustc 1.44.0-nightly (7f3df5772 2020-04-16)
binary: rustc
commit-hash: 7f3df5772439eee1c512ed2eb540beef1124d236
commit-date: 2020-04-16
host: x86_64-unknown-linux-gnu
release: 1.44.0-nightly
LLVM version: 9.0

Error output

Backtrace

thread 'rustc' panicked at 'src/librustc_incremental/persist/fs.rs:569: unexpected incr-comp session dir: /home/joshua/src/rust/gz-ice/target/debug/incremental/gz_ice-1ozj25zbd5kq1/s-fmyyvvfq9d-5g7yck.lock.gz', src/librustc_middle/util/bug.rs:37:26
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1504
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:515
  12: std::panicking::begin_panic
  13: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
  14: rustc_middle::ty::context::tls::with_opt::{{closure}}
  15: rustc_middle::ty::context::tls::with_opt
  16: rustc_middle::util::bug::opt_span_bug_fmt
  17: rustc_middle::util::bug::bug_fmt
  18: rustc_incremental::persist::fs::find_source_directory_in_iter::{{closure}}
  19: rustc_incremental::persist::fs::prepare_session_directory
  20: rustc_interface::passes::register_plugins
  21: rustc_interface::queries::Queries::register_plugins
  22: rustc_interface::interface::run_compiler_in_existing_thread_pool
  23: scoped_tls::ScopedKey<T>::set
  24: rustc_ast::attr::with_globals