"flutter upgrade" has weird output when upgrading

[Hixie]

I ran flutter upgrade to update from 1.4.9-hotfix.1 to 1.5.4 on the beta channel. Here is the output.

ianh@ianh:~/dev/test-install/flutter$ bin/flutter upgrade
Upgrading Flutter from /usr/local/google/home/ianh/dev/test-install/flutter...
From https://github.com/flutter/flutter
 + 88fa7ea40...b593f5167 beta       -> origin/beta  (forced update)
Updating 16a16e659..b593f5167
 packages/flutter/res/values/strings_en.arb         |   0
 321 files changed, 9788 insertions(+), 1534 deletions(-)

Upgrading engine...
Downloading Dart SDK from Flutter engine ca31a7c57bada458fa7f5c0d3f36bc1af4ccbc79...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed

  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
  3  120M    3 4112k    0     0  5298k      0  0:00:23 --:--:--  0:00:23 5292k
 33  120M   33 40.0M    0     0  23.4M      0  0:00:05  0:00:01  0:00:04 23.4M
 92  120M   92  111M    0     0  41.5M      0  0:00:02  0:00:02 --:--:-- 41.5M
100  120M  100  120M    0     0  43.4M      0  0:00:02  0:00:02 --:--:-- 43.4M
Building flutter tool...
Downloading android-arm-profile/linux-x64 tools...                  0.6s
Downloading android-arm-release/linux-x64 tools...                  0.6s
Downloading android-arm64-profile/linux-x64 tools...                0.5s
Downloading android-arm64-release/linux-x64 tools...                0.4s
Downloading android-arm-dynamic-profile/linux-x64 tools...          0.4s
Downloading android-arm-dynamic-release/linux-x64 tools...          0.4s
Downloading android-arm64-dynamic-profile/linux-x64 tools...         0.5s
Downloading android-arm64-dynamic-release/linux-x64 tools...         0.4s
Downloading android-x86 tools...                                    1.3s
Downloading android-x64 tools...                                    1.6s
Downloading android-arm tools...                                    0.8s
Downloading android-arm-profile tools...                            0.7s
Downloading android-arm-release tools...                            0.5s
Downloading android-arm64 tools...                                  0.8s
Downloading android-arm64-profile tools...                          0.7s
Downloading android-arm64-release tools...                          0.6s
Downloading android-arm-dynamic-profile tools...                    0.7s
Downloading android-arm-dynamic-release tools...                    0.5s
Downloading android-arm64-dynamic-profile tools...                  0.9s
Downloading android-arm64-dynamic-release tools...                  0.7s
Downloading package sky_engine...                                   0.3s
Downloading common tools...                                         2.2s
Downloading common tools...                                         0.9s
Downloading linux-x64 tools...                                      1.6s

Flutter 1.4.9-hotfix.1 • channel beta • https://github.com/flutter/flutter.git
Framework • revision 88fa7ea403 (4 days ago) • 2019-04-22 07:51:33 -0700
Engine • revision ca31a7c57b
Tools • Dart 2.2.1 (build 2.2.1-dev.4.0 None)

Running flutter doctor...
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel beta, v1.5.4, on Linux, locale en_US.UTF-8)
[!] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    ! Some Android licenses not accepted.  To resolve this, run: flutter doctor --android-licenses
[!] Android Studio (version 2.3)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[✓] IntelliJ IDEA Community Edition (version 2017.3)
[!] Connected device
    ! No devices available

! Doctor found issues in 3 categories.

This part in particular is confusing:

Updating 16a16e659..b593f5167
 packages/flutter/res/values/strings_en.arb         |   0
 321 files changed, 9788 insertions(+), 1534 deletions(-)

(The other confusing thing is #22254.)