Use BAZEL_SH if available instead of hard-coding bash in git.bzl
Use BAZEL_SH if available instead of hard-coding bash in git.bzl

Fixes #3699.

Change-Id: I44028476be96037334a1ae48de450d625925676f
PiperOrigin-RevId: 181962926

dslomov/bazel,ulfjack/bazel,dslomov/bazel,akira-baruah/bazel,ButterflyNetwork/bazel,dropbox/bazel,dslomov/bazel,dslomov/bazel-windows,perezd/bazel,perezd/bazel,davidzchen/bazel,werkt/bazel,meteorcloudy/bazel,twitter-forks/bazel,akira-baruah/bazel,katre/bazel,safarmer/bazel,perezd/bazel,davidzchen/bazel,dropbox/bazel,aehlig/bazel,bazelbuild/bazel,bazelbuild/bazel,dslomov/bazel-windows,aehlig/bazel,dslomov/bazel-windows,ulfjack/bazel,twitter-forks/bazel,ulfjack/bazel,davidzchen/bazel,aehlig/bazel,safarmer/bazel,perezd/bazel,bazelbuild/bazel,ulfjack/bazel,meteorcloudy/bazel,katre/bazel,safarmer/bazel,meteorcloudy/bazel,bazelbuild/bazel,katre/bazel,katre/bazel,twitter-forks/bazel,meteorcloudy/bazel,ulfjack/bazel,werkt/bazel,cushon/bazel,perezd/bazel,cushon/bazel,perezd/bazel,dslomov/bazel,twitter-forks/bazel,davidzchen/bazel,safarmer/bazel,aehlig/bazel,dropbox/bazel,dslomov/bazel,aehlig/bazel,werkt/bazel,cushon/bazel,ButterflyNetwork/bazel,safarmer/bazel,ulfjack/bazel,ButterflyNetwork/bazel,perezd/bazel,meteorcloudy/bazel,meteorcloudy/bazel,akira-baruah/bazel,davidzchen/bazel,werkt/bazel,akira-baruah/bazel,bazelbuild/bazel,bazelbuild/bazel,davidzchen/bazel,cushon/bazel,akira-baruah/bazel,twitter-forks/bazel,safarmer/bazel,werkt/bazel,katre/bazel,cushon/bazel,dropbox/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,akira-baruah/bazel,dslomov/bazel,ButterflyNetwork/bazel,dslomov/bazel-windows,dropbox/bazel,dslomov/bazel-windows,dslomov/bazel-windows,dropbox/bazel,aehlig/bazel,werkt/bazel,davidzchen/bazel,meteorcloudy/bazel,aehlig/bazel,ButterflyNetwork/bazel,katre/bazel,cushon/bazel,twitter-forks/bazel,dslomov/bazel,ulfjack/bazel