[`pylint`] Remove `try` body from branch counting (#11487)

## Summary

Matching Pylint, we now omit the `try` body itself from branch counting.
Each `except` counts as a branch, as does the `else` and the `finally`.

Closes https://github.com/astral-sh/ruff/issues/11205.

crates/ruff_linter/resources/test/fixtures/pylint/too_many_branches.py

@@ -21,6 +21,8 @@ def wrong(): # [too-many-branches]
         pass
     try:
         pass
+    except Exception:
+        pass
     finally:
         pass
     if 2:
@@ -56,6 +58,8 @@ def good():
         pass
     try:
         pass
+    except Exception:
+        pass
     finally:
         pass
     if 1:
@@ -90,6 +94,8 @@ def with_statement_wrong():
             pass
         try:
             pass
+        except Exception:
+            pass
         finally:
             pass
         if 2:

crates/ruff_linter/src/rules/pylint/rules/too_many_branches.rs

@@ -199,7 +199,9 @@ fn num_branches(stmts: &[Stmt]) -> usize {
                 finalbody,
                 ..
             }) => {
-                1 + num_branches(body)
+                // Count each `except` clause as a branch; the `else` and `finally` clauses also
+                // count, but the `try` clause itself does not.
+                num_branches(body)
                     + (if orelse.is_empty() {
                         0
                     } else {
@@ -323,6 +325,47 @@ return 1
         Ok(())
     }
 
+    #[test]
+    fn try_except() -> Result<()> {
+        let source: &str = r"
+try:
+    pass
+except:
+    pass
+";
+
+        test_helper(source, 1)?;
+        Ok(())
+    }
+
+    #[test]
+    fn try_except_else() -> Result<()> {
+        let source: &str = r"
+try:
+    pass
+except:
+    pass
+else:
+    pass
+";
+
+        test_helper(source, 2)?;
+        Ok(())
+    }
+
+    #[test]
+    fn try_finally() -> Result<()> {
+        let source: &str = r"
+try:
+    pass
+finally:
+    pass
+";
+
+        test_helper(source, 1)?;
+        Ok(())
+    }
+
     #[test]
     fn try_except_except_else_finally() -> Result<()> {
         let source: &str = r"
@@ -338,7 +381,7 @@ finally:
     pass
 ";
 
-        test_helper(source, 5)?;
+        test_helper(source, 4)?;
         Ok(())
     }
 

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLR0912_too_many_branches.py.snap

@@ -10,12 +10,12 @@ too_many_branches.py:8:5: PLR0912 Too many branches (13 > 12)
 10 |     if 1:
    |
 
-too_many_branches.py:76:5: PLR0912 Too many branches (13 > 12)
+too_many_branches.py:80:5: PLR0912 Too many branches (13 > 12)
    |
-74 |         pass
-75 | 
-76 | def with_statement_wrong():
+78 |         pass
+79 | 
+80 | def with_statement_wrong():
    |     ^^^^^^^^^^^^^^^^^^^^ PLR0912
-77 |     """statements inside the with statement should get counted"""
-78 |     with suppress(Exception):
+81 |     """statements inside the with statement should get counted"""
+82 |     with suppress(Exception):
    |