[minor] set_posting_time=1 only when imported data contains posting date. (#9349)

diff --git a/erpnext/utilities/transaction_base.py b/erpnext/utilities/transaction_base.py
index 256f847..0e3a4f9 100644
--- a/erpnext/utilities/transaction_base.py
+++ b/erpnext/utilities/transaction_base.py
@@ -19,7 +19,7 @@
 
 	def validate_posting_time(self):
 		# set Edit Posting Date and Time to 1 while data import
-		if frappe.flags.in_import:
+		if frappe.flags.in_import and self.posting_date:
 			self.set_posting_time = 1
 
 		if not getattr(self, 'set_posting_time', None):