Eliminate repetitive line/column context from error message

src/libyaml/error.rs

@@ -72,7 +72,10 @@ impl Display for Error {
         }
         if let Some(context) = &self.context {
             write!(formatter, ", {}", context)?;
-            if self.context_mark.sys.line != 0 || self.context_mark.sys.column != 0 {
+            if (self.context_mark.sys.line != 0 || self.context_mark.sys.column != 0)
+                && (self.context_mark.sys.line != self.problem_mark.sys.line
+                    || self.context_mark.sys.column != self.problem_mark.sys.column)
+            {
                 write!(formatter, " at {}", self.context_mark)?;
             }
         }

tests/test_error.rs

@@ -132,7 +132,7 @@ fn test_second_document_syntax_error() {
 
     let second_doc = de.next().unwrap();
     let result = <usize as serde::Deserialize>::deserialize(second_doc);
-    let expected = "did not find expected node content at line 4 column 1, while parsing a block node at line 4 column 1";
+    let expected = "did not find expected node content at line 4 column 1, while parsing a block node";
     assert_eq!(expected, result.unwrap_err().to_string());
 }