Fixed epoch parser failing for numeric values

Signed-off-by: Omkar Phansopkar <omkarphansopkar@gmail.com>

Author: OmkarPh

src/packagedcode/rpm.py

@@ -96,6 +96,9 @@ def __new__(self, version, release=None, epoch=None):
         note: the sort order of the named tuple is the sort order.
         But for creation we put the rarely used epoch last with a default to None.
         """
+        
+        epoch = str(epoch) if epoch else ""
+
         if epoch and epoch.strip() and not epoch.isdigit():
             raise ValueError('Invalid epoch: must be a number or empty.')
         if not version:

tests/packagedcode/data/rpm/header/apache-commons-io-2.4-12.el7.noarch.rpm

@@ -0,0 +1,19 @@
+{
+    "name": "apache-commons-io",
+    "epoch": "1",
+    "version": "2.4",
+    "release": "12.el7",
+    "arch": "noarch",
+    "os": "linux",
+    "summary": "Utilities to assist with developing IO functionality",
+    "description": null,
+    "distribution": null,
+    "vendor": "CentOS",
+    "license": "ASL 2.0",
+    "packager": "CentOS BuildSystem <http://bugs.centos.org>",
+    "group": "Unspecified",
+    "url": "http://commons.apache.org/io",
+    "source_rpm": "apache-commons-io-2.4-12.el7.src.rpm",
+    "dist_url": null,
+    "is_binary": true
+}

tests/packagedcode/data/rpm/header/apache-commons-io-2.4-12.el7.noarch.rpm-expected.json

@@ -391,3 +391,7 @@ def test_rpm_tags_xsetup_0_28_b1_src_rpm(self):
     def test_rpm_tags_zziplib_0_11_15_3sf_i586_rpm(self):
         test_file = self.get_test_loc('rpm/header/zziplib-0.11.15-3sf.i586.rpm')
         self.check_rpm_tags(test_file)
+
+    def test_rpm_tags_apache_commons_io_2_4_12_el7_noarch_rpm(self):
+        test_file = self.get_test_loc('rpm/header/apache-commons-io-2.4-12.el7.noarch.rpm')
+        self.check_rpm_tags(test_file)