net-installer: try harder to install packages

SourceForge -- which backs MSys2's own packages -- could be a little
more reliable, meaning that Pacman sometimes errors out because packages
could either not be downloaded at all, or downloads got interrupted, or
just got too slow.

To work around this issue, let's try up to five times to install
packages, and if it still did not work, notify the user and give up.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

net-installer/setup-git-sdk.bat

@@ -13,14 +13,45 @@
 @REM set MSYSTEM so that MSys2 starts up in the correct mode
 @set MSYSTEM=MINGW@@BITNESS@@
 
+@SET /A counter=0
+:INSTALL_RUNTIME
+@SET /A counter+=1
+@IF %counter% GEQ 5 (
+	@ECHO "Could not install msys2-runtime"
+	@PAUSE
+	@EXIT 1
+)
+
 @REM update the Pacman package indices first, then force-install msys2-runtime
 @REM (we ship with a stripped-down msys2-runtime, gpg and pacman), so that
 @REM pacman's post-install scripts run without complaining about heap problems
 @%cwd%\usr\bin\pacman -Sy --force --noconfirm msys2-runtime
 
+@IF ERRORLEVEL 1 GOTO INSTALL_RUNTIME
+
+@SET /A counter=0
+:INSTALL_PACMAN
+@SET /A counter+=1
+@IF %counter% GEQ 5 (
+	@ECHO "Could not install pacman"
+	@PAUSE
+	@EXIT 1
+)
+
 @REM next, force update pacman
 @%cwd%\usr\bin\pacman -S --force --noconfirm pacman
 
+@IF ERRORLEVEL 1 GOTO INSTALL_PACMAN
+
+@SET /A counter=0
+:INSTALL_REST
+@SET /A counter+=1
+@IF %counter% GEQ 5 (
+	@ECHO "Could not install the remaining packages"
+	@PAUSE
+	@EXIT 1
+)
+
 @REM now update the rest
 @%cwd%\usr\bin\pacman -S --force --noconfirm ^
 	base python less openssh patch make tar diffutils ca-certificates ^
@@ -32,6 +63,8 @@
 	mingw-w64-@@ARCH@@-openssl mingw-w64-@@ARCH@@-tcl ^
 	mingw-w64-@@ARCH@@-pcre
 
+@IF ERRORLEVEL 1 GOTO INSTALL_REST
+
 @REM Avoid overlapping address ranges
 @IF MINGW32 == %MSYSTEM% (
 	ECHO "Auto-rebasing .dll files"