Index: usr.sbin/etcupdate/etcupdate.sh
===================================================================
--- usr.sbin/etcupdate/etcupdate.sh
+++ usr.sbin/etcupdate/etcupdate.sh
@@ -871,6 +871,76 @@
 	egrep -q '^(<{7}|\|{7}|={7}|>{7}) ' $CONFLICTS/$1
 }
 
+# We create a "database" of passwords for users. We don't save actual
+# hashes to any variable to not leek them through process list.
+#
+# $1 - pathname to the file from which database should be created
+create_user_database()
+{
+	awk '
+	BEGIN {
+		FS = ":"
+	}
+	{
+		if ($1 ~ "^#" || NF < 10)
+			next
+		printf("%s:", $1)
+		if ($2 ~ "^[a-zA-Z0-9*/$.]+$")
+			printf("yes\n")
+		else
+			printf("no\n")
+	}
+	' $1
+}
+
+# Check if user mistakenly didn't remove the password
+#
+# $1 - filename of current analyzed file
+# $2 - directory from which take a new version of file
+check_passwd()
+{
+	local filename newdir junk
+	local newdb olddb
+	local username newpass
+	local olduser oldcount oldpass
+
+	filename="$1"
+	newdir="$2"
+
+	if [ "${filename}" != "/etc/master.passwd" ]; then
+		return 0
+	fi
+
+	newdb=`create_user_database "${newdir}${filename}"`
+	olddb=`create_user_database "${DESTDIR}${filename}"`
+
+	for user in $newdb; do
+		username=`echo "${user}" | cut -d":" -f1`
+		newpass=`echo "${user}" | cut -d":" -f2`
+
+		olduser=`echo "${olddb}" | grep "^${username}:"`
+		oldcount=`echo "${olduser}" | wc -l`
+		if [ "${oldcount}" -eq 0 ]; then
+			# User doesn't exists in old db. Skipping.
+			continue
+		elif [ "${oldcount}" -ne 1 ]; then
+			panic "Unable to check file ${filename}." \
+			    "Multiple records for user ${username}"
+		fi
+
+		oldpass=`echo "${olduser}" | cut -d":" -f2`
+		if [ "${oldpass}" != "${newpass}" -a "${newpass}" = "no" ]; then
+			echo "After merge, '${username}' has no password," \
+			    "do you want to continue? (y/n) "
+			read junk
+			if [ "${junk}" != "y" ]; then
+				return 1
+			fi
+		fi
+	done
+	return 0
+}
+
 # Attempt to resolve a conflict.  The user is prompted to choose an
 # action for each conflict.  If the user edits the file, they are
 # prompted again for an action.  The process is very similar to
@@ -935,6 +1005,10 @@
 					fi
 				fi
 
+				if ! check_passwd $1 ${CONFLICTS}; then
+					continue
+				fi
+
 				if ! install_resolved $1; then
 					panic "Unable to install merged" \
 					    "version of $1"
@@ -946,6 +1020,11 @@
 				# For theirs-full, install the new
 				# version of the file over top of the
 				# existing file.
+
+				if ! check_passwd $1 ${NEWTREE}; then
+					continue
+				fi
+
 				if ! install_new $1; then
 					panic "Unable to install new" \
 					    "version of $1"