[win-bootstrap] Update the comments in update_depot_tools.bat

Also adds an echo to win_tools.bat so a user will know when the
bootstrapping script is skipped after a CIPD install error.
This should hopefully help when troubleshooting.

Bug: b/360206460
Change-Id: Ic8bfcbddfe4681a7716ca9f3793d045e0de704cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6242904
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Commit-Queue: Anne Redulla <aredulla@google.com>

bootstrap/win_tools.bat

@@ -58,9 +58,12 @@ set BOOTSTRAP_EXTRA_ARGS=--bootstrap-name "%BOOTSTRAP_NAME%"
 :: See "//cipd.bat" and "//.cipd_impl.ps1" for more information.
 set CIPD_EXE=%BOOTSTRAP_ROOT_DIR%\cipd.bat
 call "%CIPD_EXE%" ensure -log-level warning -ensure-file "%~dp0%CIPD_MANIFEST%" -root "%BOOTSTRAP_PATH%"
-if errorlevel 1 goto :END
+if errorlevel 1 (
+  echo Error installing CIPD packages.
+  goto :END
+)
 
-:: This executes "win_tools.py" using the bundle's Python interpreter.
+:: This executes "bootstrap.py" using the bundle's Python interpreter.
 set BOOTSTRAP_PYTHON_BIN=%BOOTSTRAP_PATH%\python3\bin\python3.exe
 call "%BOOTSTRAP_PYTHON_BIN%" "%~dp0bootstrap.py" %BOOTSTRAP_EXTRA_ARGS%
 

update_depot_tools.bat

@@ -34,12 +34,15 @@ IF "%DEPOT_TOOLS_UPDATE%" == "0" GOTO :EOF
 
 echo Updating depot_tools...
 
-:: Download git for the first time if it's not present.
+:: Trigger generating depot_tools' git wrappers in case they are in a bad state.
+:: This can happen if there was a problem installing CIPD packages in the
+:: previous attempt to update depot_tools, and the bootstrapping script was not
+:: run.
 call git --version > nul 2>&1
 if %ERRORLEVEL% == 0 goto :GIT_UPDATE
 call "%DEPOT_TOOLS_DIR%bootstrap\win_tools.bat"
 if errorlevel 1 (
-  echo Error updating depot_tools, no revision tool found.
+  echo Error updating depot_tools - Git not found.
   exit /b %ERRORLEVEL%
 )
 
@@ -65,5 +68,5 @@ if errorlevel 1 (
 :: Sync CIPD and CIPD client tools.
 call "%~dp0\cipd_bin_setup.bat"
 
-:: Update git and python.
+:: Update python and generate git wrappers.
 call "%DEPOT_TOOLS_DIR%bootstrap\win_tools.bat"