Some Rust packages build a lot of stuff during do_install

At least rust-analyzer and angle-grinder. Example below

=> rust-analyzer-2021.03.01_2: running do_install ...
  Installing rust-analyzer v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/rust-analyzer)
    Updating crates.io index
warning: package `pin-project-lite v0.2.4` in Cargo.lock is yanked in registry `crates.io`, consider running without --locked
   Compiling once_cell v1.7.0
warning: Could not find `.git/HEAD` from manifest dir!
   Compiling countme v2.0.4
   Compiling thread_local v1.1.3
   Compiling profile v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/profile)
   Compiling rowan v0.12.6
   Compiling tracing-subscriber v0.2.16
   Compiling test_utils v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/test_utils)
   Compiling syntax v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/syntax)
   Compiling tracing-tree v0.1.8
   Compiling chalk-solve v0.58.0
   Compiling base_db v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/base_db)
   Compiling mbe v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/mbe)
   Compiling proc_macro_api v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/proc_macro_api)
   Compiling hir_expand v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/hir_expand)
   Compiling project_model v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/project_model)
   Compiling proc_macro_srv v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/proc_macro_srv)
   Compiling chalk-recursive v0.58.0
   Compiling hir_def v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/hir_def)
   Compiling hir_ty v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/hir_ty)
   Compiling hir v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/hir)
   Compiling ide_db v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/ide_db)
   Compiling ide_assists v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/ide_assists)
   Compiling ide_ssr v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/ide_ssr)
   Compiling ide_completion v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/ide_completion)
   Compiling ide v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/ide)
   Compiling rust-analyzer v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/rust-analyzer)
    Finished release [optimized] target(s) in 4m 07s
  Installing /destdir//rust-analyzer-2021.03.01/usr/bin/rust-analyzer
   Installed package `rust-analyzer v0.0.0 (/builddir/rust-analyzer-2021-03-01/crates/rust-analyzer)` (executable `rust-analyzer`)
warning: be sure to add `/destdir//rust-analyzer-2021.03.01/usr/bin` to your PATH to be able to run the installed binaries
=> rust-analyzer-2021.03.01_2: running post_install ...

Start by locating the package definitions for rust-analyzer and angle-grinder and tracing their do_install entry points. Reproduce one of the builds and compare the work performed during do_install with the earlier build phases. Done means do_install installs the package without rebuilding its Rust dependencies or workspace.