When running the `./tools/cache-zulip-git-version` script on Travis, the script
fails because Travis gets a shallow clone of the repository, and not a full
clone. This commit changes the script to fail gracefully, if we are unable to
get the version information using `git describe`.
When the command fails, it still writes an empty `zulip-git-version` and that
has not been changed to keep creation of the release tarball simple, and
avoiding a check for whether the file has any content. The code that sets
`ZULIP_VERSION` checks whether the contents of the `zulip-git-version` file are
empty, before setting `ZULIP_VERSION`. So, the version should never be set to an
empty string.
We use `git describe --tags` to get information about the number of commit since
the last major version, and the sha of the current HEAD. This is added to the
ZULIP_VERSION when a deploy is done from `git`.
Modified heavily by punchagan to:
* to use git describe instead of `git log` and `wc`
* use a separate script to run the git describe command
* write the file with version info to var/ and remove it from the repo
Fixes#4685.
Puneeth Chaganti
ppreethi