Do not throw away backpack instantiations for module lookup cache

Currently, there is only one home package so this probably doesn't
matter. But if we support multiple home packages, they could differ only
in arguments (same indef component being applied).

It looks like it used to be this way before
4e8a0607, but that commit doesn't seem
to comment on this change in the particular. (It's main purpose is
creating the InstalledUnitId and recategorizing the UnitId expressions
accordingly.)

Trying this as a separate commit for testing purposes. I leave it to
others to decide whether this is a good change on its own.
21 jobs for master in 313 minutes and 57 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Lint
passed #154336
lint
lint-linters

00:00:21

passed #154339
lint
lint-submods-branch

00:00:15

passed #154337
lint
lint-testsuite

00:00:16

passed #154338
lint
typecheck-testsuite

00:00:14

 
  Build
passed #154341
x86_64-linux
hadrian-ghc-in-ghci

00:21:18

passed #154343
x86_64-linux
release-x86_64-linux-deb9-dwarf

01:41:31

passed #154342
x86_64-linux
validate-x86_64-linux-deb9-debug

01:40:34

passed #154340
x86_64-linux
validate-x86_64-linux-deb9-hadrian

03:16:17

 
  Full Build
failed #154345
aarch64-linux allowed to fail
validate-aarch64-linux-deb9

01:02:11

passed #154346
x86_64-linux
validate-i386-linux-deb9

00:41:50

passed #154344
x86_64-darwin
validate-x86_64-darwin

01:11:21

passed #154347
x86_64-linux
validate-x86_64-linux-deb9-integer-simple

01:27:58

passed #154348
x86_64-linux
validate-x86_64-linux-deb9-unreg

01:20:34

passed #154349
x86_64-linux
validate-x86_64-linux-fedora27

01:29:40

failed #154351
x86_64-windows allowed to fail
validate-x86_64-windows

00:00:03

failed #154350
x86_64-windows allowed to fail
validate-x86_64-windows-hadrian

00:00:03

 
  Cleanup
passed #154352
x86_64-darwin
cleanup-darwin

00:00:06

 
  Packaging
failed #154353
x86_64-linux allowed to fail
doc-tarball

00:00:19

 
  Testing
manual #154354
x86_64-linux allowed to fail manual
hackage
passed #154355
x86_64-linux
perf-nofib

00:25:03

 
  Deploy
failed #154356
x86_64-linux allowed to fail
pages

00:01:54

 
Name Stage Failure
failed
validate-x86_64-windows-hadrian Full Build
Runtime platform                                    arch=amd64 os=windows pid=4984 revision=1f513601 version=11.10.1
WARNING: ghc.tar.xz: no matching files
WARNING: junit.xml: no matching files
ERROR: No files to upload
Uploading artifacts...
Runtime platform
arch=amd64 os=windows pid=5404 revision=1f513601 version=11.10.1
WARNING: junit.xml: no matching files
ERROR: No files to upload
ERROR: Job failed: exit status 1
failed
validate-x86_64-windows Full Build
Runtime platform                                    arch=amd64 os=windows pid=1336 revision=1f513601 version=11.10.1
WARNING: ghc-*.tar.xz: no matching files
WARNING: junit.xml: no matching files
ERROR: No files to upload
Uploading artifacts...
Runtime platform
arch=amd64 os=windows pid=3724 revision=1f513601 version=11.10.1
WARNING: junit.xml: no matching files
ERROR: No files to upload
ERROR: Job failed: exit status 1
failed
validate-aarch64-linux-deb9 Full Build
$ cp -Rf $HOME/.cabal cabal-cache
Uploading artifacts...
WARNING: ghc-*.tar.xz: no matching files
WARNING: junit.xml: no matching files
ERROR: No files to upload
Uploading artifacts...
WARNING: junit.xml: no matching files
ERROR: No files to upload
ERROR: Job failed: exit code 1
failed
doc-tarball Packaging
Synchronizing submodule url for 'utils/hsc2hs'
$ git submodule update --init --recursive
$ git checkout .gitmodules
$ git fetch https://gitlab.haskell.org/ghc/ghc-performance-notes.git refs/notes/perf:refs/notes/perf || true
From https://gitlab.haskell.org/ghc/ghc-performance-notes
9a5525102a..78c36f2d21 refs/notes/perf -> refs/notes/perf
$ if [ ! -f "$LINUX_BINDIST" ]; then # collapsed multi-line command
Error: ghc-x86_64-mingw32.tar.xz does not exist. Did the 64-bit Windows job fail?
ERROR: Job failed: exit code 1
failed
pages Deploy
Synchronizing submodule url for 'utils/hsc2hs'
$ git submodule update --init --recursive
$ git checkout .gitmodules
$ git fetch https://gitlab.haskell.org/ghc/ghc-performance-notes.git refs/notes/perf:refs/notes/perf || true
$ mkdir -p public/doc
$ tar -xf haddock.html.tar.xz -C public/doc
tar: haddock.html.tar.xz: Cannot open: No such file or directory
tar: Error is not recoverable: exiting now
ERROR: Job failed: exit code 1