Suppress unwanted errors

When there are multiple revisions of an imported module, they are all parsed, and the logic to suppress errors fails to suppress them from the revisions that aren't selected for import. This fix works around this.

bin/pyang

@@ -450,9 +450,9 @@ Validates the YANG module in <filename> (or stdin), and all its dependencies."""
         if etag in o.ignore_error_tags:
             continue
         if (ctx.implicit_errors is False and
-            hasattr(epos.top, 'i_modulename') and
             epos.top.arg not in modulenames and
-            epos.top.i_modulename not in modulenames and
+            (not hasattr(epos.top, 'i_modulename') or
+             epos.top.i_modulename not in modulenames) and
             epos.ref not in filenames):
             # this module was added implicitly (by import); skip this error
             # the code includes submodules

test/test_issues/test_i680/makefile

@@ -0,0 +1,4 @@
+test: test1
+
+test1:
+	-$(PYANG) --max-line-len=70 -f tree -o mod1.tree mod1.yang 2>&1 | diff mod1.expect -

test/test_issues/test_i680/mod1.tree

@@ -0,0 +1,4 @@
+
+module: mod1
+  augment /m2:a:
+    +--rw b

test/test_issues/test_i680/mod1.yang

@@ -0,0 +1,13 @@
+module mod1 {
+  yang-version 1.1;
+  namespace "urn:mod1";
+  prefix m1;
+
+  import mod2 {
+    prefix m2;
+  }
+
+  augment "/m2:a" {
+    container b {}
+  }
+}

test/test_issues/test_i680/mod2.yang

@@ -0,0 +1 @@
+mod2@2020-10-06.yang

test/test_issues/test_i680/mod2@2020-10-06.yang

@@ -0,0 +1,13 @@
+module mod2 {
+  yang-version 1.1;
+  namespace "urn:mod2";
+  prefix m2;
+
+  revision 2020-10-06;
+
+  container a {
+    description
+      "This line is rather over-long, and therefore will trigger a warning with
+       --max-line-length=70.";
+  }
+}