Reland "Make depot_tools scripts return exit codes properly on all platforms."

This reverts commit 6754c49e02.

Reason for revert: will be relanded with fixed batch comments that triggered parser error.

Original change's description:
> Revert "Make depot_tools scripts return exit codes properly on all platforms."
>
> This reverts commit 7c4f7ec408.
>
> Reason for revert: bugs reported by users (see comments in Gerrit).
> error: block. was unexpected at this time.
>
> Original change's description:
> > Make depot_tools scripts return exit codes properly on all platforms.
> >
> > Changes:
> > 1. Windows: exit /b %errorlevel% should be used instead of goto :EOF to get valid exit codes during cmd /c <script>.bat invocation.
> > 2. Windows: delayed var expansion is required in update_depot_tools.bat exit code generation.
> > 3. Posix: update_depot_tools returns exit code from update_git_repo function in case of a failure.
> >
> > A rule of thumb on Windows: goto :EOF should not be used if %errorlevel% must be returned for all possible invocations.
> >
> > Test case for update_depot_tools changes:
> > 1. Make a change to depot_tools sources that will conflict with next depot_tools update
> > 2. Run update_depot_tools either directly or via gclient
> > 3. Expect a git error is triggered
> > 4. Inspect %errorlevel% or $? depending on platform
> > 5. Expected 1, but the actual result is 0.
> >
> > Test case for changes in other .bat files:
> > 1. Make a change to depot_tools sources that will conflict with next depot_tools update
> > 2. Run cmd /c gclient
> > 3. Expect a git error is triggered
> > 4. Inspect %errorlevel%
> > 5. Expected 1, but the actual result is 0.
> >
> > Change-Id: I64459982bcd9cc3db1319a9b39224b7a7af8c5aa
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3688632
> > Reviewed-by: Josip Sokcevic <sokcevic@google.com>
> > Commit-Queue: Josip Sokcevic <sokcevic@google.com>
> > Auto-Submit: Aleksey Khoroshilov <akhoroshilov@brave.com>
> > Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
>
> Change-Id: I85d598af01d75588cdee77165d6af22270ee031d
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3694139
> Auto-Submit: Josip Sokcevic <sokcevic@google.com>
> Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

Change-Id: I377f966ea1b1a567de815caca703b5e124a76b64
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3696396
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Auto-Submit: Aleksey Khoroshilov <akhoroshilov@brave.com>

update_depot_tools.bat

@@ -5,19 +5,26 @@
 
 :: This batch file will try to sync the root directory.
 
-setlocal
+setlocal enabledelayedexpansion
 
 :: Windows freaks out if a file is overwritten while it's being executed.  Copy
 :: this script off to a temporary location and reinvoke from there before
 :: running any git commands.
+:: !ERRORLEVEL! syntax is used to get delayed expansion, because %ERRORLEVEL%
+:: would return a value that was set prior entering the IF block.
 IF "%~nx0"=="update_depot_tools.bat" (
   COPY /Y "%~dp0update_depot_tools.bat" "%TEMP%\update_depot_tools_tmp.bat" >nul
-  if errorlevel 1 goto :EOF
+  if errorlevel 1 (
+    echo Error updating depot_tools, can't copy update_depot_tools.bat to TEMP.
+    exit /b !ERRORLEVEL!
+  )
   :: Use call/exit to avoid leaving an orphaned window title.
   call "%TEMP%\update_depot_tools_tmp.bat" "%~dp0" %*
-  exit /b %ERRORLEVEL%
+  exit /b !ERRORLEVEL!
 )
 
+setlocal disabledelayedexpansion
+
 set DEPOT_TOOLS_DIR=%~1
 SHIFT
 
@@ -25,15 +32,16 @@ SHIFT
 IF EXIST "%DEPOT_TOOLS_DIR%.disable_auto_update" GOTO :EOF
 IF "%DEPOT_TOOLS_UPDATE%" == "0" GOTO :EOF
 
+echo Updating depot_tools...
 set GIT_URL=https://chromium.googlesource.com/chromium/tools/depot_tools.git
 
 :: Download git for the first time if it's not present.
 call git --version > nul 2>&1
-if %errorlevel% == 0 goto :GIT_UPDATE
+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.
-  goto :EOF
+  exit /b %ERRORLEVEL%
 )
 
 :GIT_UPDATE
@@ -60,7 +68,7 @@ call git fetch -q origin > NUL
 call git checkout -q origin/main > NUL
 if errorlevel 1 (
   echo Failed to update depot_tools.
-  goto :EOF
+  exit /b %ERRORLEVEL%
 )
 
 :: Sync CIPD and CIPD client tools.