coverage erase: add -c as well

Author: nbfalcon

coverage/cmdline.py

@@ -384,7 +384,7 @@ def get_prog_name(self):
     ),
 
     'erase': CmdOptionParser(
-        "erase", GLOBAL_ARGS,
+        "erase", [Opts.input_coverage] + GLOBAL_ARGS,
         description="Erase previously collected coverage data.",
     ),
 

tests/test_cmdline.py

@@ -307,6 +307,10 @@ def test_erase(self):
             cov = Coverage()
             cov.erase()
             """)
+        self.cmd_executes("erase -c foo.cov", """\
+            cov = Coverage(data_file="foo.cov")
+            cov.erase()
+            """)
 
     def test_version(self):
         # coverage --version