WIP: try to work around clone failures

For some reason, this developer experiences a lot of clone failures. The
tell-tale is that the exit code is 128, but sometimes, confusingly, the
clone works, and the exit code is 0.

It appears that trying to debug this by setting GIT_CURL_VERBOSE=1
(possibly in conjunction with GIT_TRANSPORT_HELPER_DEBUG=1) makes it
more likely to pass.

It could well be that this bug is related to another bug: The progress
while the clone transfers objects is not shown (probably because of a
failing isatty() call).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

net-installer/setup-git-sdk.bat

@@ -37,6 +37,6 @@
 @IF MINGW32 == %MSYSTEM% CALL %cwd%\autorebase.bat
 
 @REM now clone the Git sources, build it, and start an interactive shell
-@mintty bash --login -c "mkdir -p /usr/src && cd /usr/src && git -c core.autocrlf=false clone -b master https://github.com/git-for-windows/git && cd git && git config core.autocrlf false && make install; bash -i"
+@mintty bash --login -c "mkdir -p /usr/src && cd /usr/src && counter=1; while test $counter -lt 5; do git -c core.autocrlf=false clone -b master https://github.com/git-for-windows/git; status=$?; test $status = 0 && break; test $status = 128 || exit $status; counter=$(($counter+1)); done && cd git && git config core.autocrlf false && make install; bash -i"
 
 @IF NOT ERRORLEVEL 0 bash --login -i