Do not pollute global base path with export genesis/wasm (#2487)

Otherwise the user may runs into weird errors if there is already a db.

cumulus/client/cli/src/lib.rs

@@ -215,6 +215,13 @@ impl sc_cli::CliConfiguration for ExportGenesisStateCommand {
 	fn shared_params(&self) -> &sc_cli::SharedParams {
 		&self.shared_params
 	}
+
+	fn base_path(&self) -> sc_cli::Result<Option<BasePath>> {
+		// As we are just exporting the genesis wasm a tmp database is enough.
+		//
+		// As otherwise we may "pollute" the global base path.
+		Ok(Some(BasePath::new_temp_dir()?))
+	}
 }
 
 /// Command for exporting the genesis wasm file.
@@ -266,6 +273,13 @@ impl sc_cli::CliConfiguration for ExportGenesisWasmCommand {
 	fn shared_params(&self) -> &sc_cli::SharedParams {
 		&self.shared_params
 	}
+
+	fn base_path(&self) -> sc_cli::Result<Option<BasePath>> {
+		// As we are just exporting the genesis wasm a tmp database is enough.
+		//
+		// As otherwise we may "pollute" the global base path.
+		Ok(Some(BasePath::new_temp_dir()?))
+	}
 }
 
 fn validate_relay_chain_url(arg: &str) -> Result<Url, String> {