zanata-cli: Failed to pull without zanata.xml

Without zanata-cli, it failed to pull

Steps to repoduce:
1. cd /tmp
2. Run `zanata-cli -e pull --url https://fedora.zanata.org/ --project ibus-chewing --project-version master --project-type gettext --disable-ssl-cert --locales zh-TW --pull-type both`

Expected:
Both source and zh-TW thanslation should be pulled

Actual:
[ERROR] Execution failed:
java.lang.NullPointerException
at org.zanata.client.commands.PushPullCommand.getLocaleMapList(PushPullCommand.java:200)
at org.zanata.client.commands.AbstractPushPullOptionsImpl.getLocaleMapList(AbstractPushPullOptionsImpl.java:63)
at org.zanata.client.commands.pull.PullCommand.logOptions(PullCommand.java:118)
at org.zanata.client.commands.pull.PullCommand.logOptions(PullCommand.java:84)
at org.zanata.client.commands.pull.PullCommand.run(PullCommand.java:144)
at org.zanata.client.commands.ConfigurableCommand.runWithActions(ConfigurableCommand.java:110)
at org.zanata.client.commands.ArgsUtil.runCommand(ArgsUtil.java:48)
at org.zanata.client.ZanataClient.processArgs(ZanataClient.java:170)
at org.zanata.client.ZanataClient.main(ZanataClient.java:95)

If the `--locales zh-TW` was not given, it returns following error:
[ERROR] Execution failed:
java.lang.NullPointerException
at org.zanata.client.commands.PushPullCommand.getLocaleMapList(PushPullCommand.java:200)
at org.zanata.client.commands.AbstractPushPullOptionsImpl.getLocaleMapList(AbstractPushPullOptionsImpl.java:63)
at org.zanata.client.commands.pull.PullCommand.logOptions(PullCommand.java:118)
at org.zanata.client.commands.pull.PullCommand.logOptions(PullCommand.java:84)
at org.zanata.client.commands.pull.PullCommand.run(PullCommand.java:144)
at org.zanata.client.commands.ConfigurableCommand.runWithActions(ConfigurableCommand.java:110)
at org.zanata.client.commands.ArgsUtil.runCommand(ArgsUtil.java:48)
at org.zanata.client.ZanataClient.processArgs(ZanataClient.java:170)
at org.zanata.client.ZanataClient.main(ZanataClient.java:95)