don't show import button if import is in progress (#4960)

frappe/core/doctype/data_import/data_import.js

@@ -60,7 +60,8 @@ frappe.ui.form.on('Data Import', {
 			});
 		}
 
-		if (frm.doc.reference_doctype && frm.doc.import_file && frm.doc.total_rows  && frm.doc.docstatus === 0) {
+		if (frm.doc.reference_doctype && frm.doc.import_file && frm.doc.total_rows &&
+			frm.doc.docstatus === 0 && (!frm.doc.import_status || frm.doc.import_status=="Failed")) {
 			frm.page.set_primary_action(__("Start Import"), function() {
 				frappe.call({
 					method: "frappe.core.doctype.data_import.data_import.import_data",

frappe/core/doctype/data_import/data_import.py

@@ -33,8 +33,11 @@ def import_data(data_import):
 	frappe.db.set_value("Data Import", data_import, "import_status", "In Progress", update_modified=False)
 	frappe.publish_realtime("data_import_progress", {"progress": "0",
 		"data_import": data_import, "reload": True}, user=frappe.session.user)
-	enqueue(upload, queue='default', timeout=6000, event='data_import',
-		data_import_doc=data_import, from_data_import="Yes", user=frappe.session.user)
+	from frappe.core.page.background_jobs.background_jobs import get_info
+	enqueued_jobs = [d.get("job_name") for d in get_info()]
+	if data_import not in enqueued_jobs:
+		enqueue(upload, queue='default', timeout=6000, event='data_import', job_name=data_import,
+			data_import_doc=data_import, from_data_import="Yes", user=frappe.session.user)
 
 
 def import_doc(path, overwrite=False, ignore_links=False, ignore_insert=False,