Upgrade git on Windows

Unfortunately git support for submodules, shallow and/or depth limited cloning
has improved in recent git versions and the Travis Windows image has an old
version of git.

Author: polytypic

.travis.yml

@@ -17,8 +17,8 @@ git:
 
 before_install:
   - export -f travis_nanoseconds travis_time_start travis_time_finish
-  - export GIT_DEPTH=$(if [ 002021000 -le $(git --version | sed -e 's#^[^0-9]*\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*$#00\1.00\2.00\3#g' -e 's#[0-9]*\([0-9]\{3\}\)\.*#\1#g') ]; then echo '--depth 1'; fi)
+  - if [ "$TRAVIS_OS_NAME" = windows ]; then choco upgrade -y git.install; fi
 
 script:
-  - if ! [ -x .cppsm/travis-ci ]; then git submodule --quiet update --init --no-recommend-shallow $GIT_DEPTH .cppsm; fi
+  - if ! [ -x .cppsm/travis-ci ]; then git submodule --quiet update --init --no-recommend-shallow --depth 1 .cppsm; fi
   - .cppsm/travis-ci

travis-ci

@@ -63,7 +63,7 @@ folded() {
   echo -e "\ntravis_fold:end:cppsm.$FOLD\r"
 }
 
-folded ... concurrently GIT_UPDATE_PID git submodule update --init $GIT_DEPTH --jobs "$N_PARALLEL_UPDATE"
+folded ... concurrently GIT_UPDATE_PID git submodule update --init --depth 1 --jobs "$N_PARALLEL_UPDATE"
 
 if [ "$TRAVIS_OS_NAME" = linux ]; then
   folded ... concurrently LIBSTD_INSTALL_PID locked bash -c 'sudo -E apt-add-repository -y ppa:ubuntu-toolchain-r/test && sudo -E apt-get -yq update && sudo -E apt-get -yq --no-install-suggests --no-install-recommends install libstdc++-8-dev'