Skip "HEAD is now at HASH" messages

[philderbeast]

With a source-repository-package, it takes three cabal build cycles for the related messages to settle down and this can be a time drain to watch and wait for if some of those packages are big, like amazonka, or if a project has many source repository packages:

1. Verbose download
2. OK acknowledging the hash
3. All good

$ cabal build all --enable-tests --enable-benchmarks
Cloning into '/.../dist-newstyle/src/monad-log_-b6a715dfba45a322'...
remote: Enumerating objects: 1376, done.
remote: Counting objects: 100% (336/336), done.
remote: Compressing objects: 100% (130/130), done.
remote: Total 1376 (delta 167), reused 301 (delta 151), pack-reused 1040
Receiving objects: 100% (1376/1376), 187.04 KiB | 3.34 MiB/s, done.
Resolving deltas: 100% (701/701), done.
HEAD is now at bfaad47 monad-logger-aeson-0.4.0.2
...

$ cabal build all --enable-tests --enable-benchmarks
HEAD is now at bfaad47 monad-logger-aeson-0.4.0.2
Up to date

$ cabal build all --enable-tests --enable-benchmarks
Up to date

Expected behavior
I suggest that after step 1 we skip step and don't mention the hashes if they've not changed.

Anxiety trigger
As I'm watching the first verbose message, I see hashes that don't match. Should I care?

- monad-log_-b6a715dfba45a322
+ bfaad47 monad-logger-aeson-0.4.0.2

Reproduction
The source-repository-package of this example:

source-repository-package
  type: git
  location: https://github.com/jship/monad-logger-aeson.git
  tag: bfaad47420dc90e3237cffc718d0b0257cf7c807
  subdir:
    monad-logger-aeson

[philderbeast]

A measure of the time it can take:

$ time cabal build all --enable-tests --enable-benchmarks --dry-run
Cloning into ...
...
________________________________________________________
Executed in   56.87 secs    fish           external
   usr time   39.80 secs    0.00 micros   39.80 secs
   sys time    7.06 secs  617.00 micros    7.06 secs

$ time cabal build all --enable-tests --enable-benchmarks --dry-run
HEAD is now at ...
...
________________________________________________________
Executed in   28.36 secs    fish           external
   usr time   15.66 secs  410.00 micros   15.66 secs
   sys time    4.06 secs  205.00 micros    4.06 secs

$ time cabal build all --enable-tests --enable-benchmarks --dry-run
Build profile: -w ghc-8.10.7 -O1:
In order, the following would be built (use -v for more details)
...
_______________________________________________________
Executed in    1.25 secs    fish           external
   usr time    1.08 secs    0.00 micros    1.08 secs
   sys time    0.17 secs  602.00 micros    0.16 secs

[philderbeast]

Prompted to mention this as it is possibly related to #9113.