Enable lints around return statements

This enables a class of return-related lints[^1] around return
statements. I mainly came here for redundant returns after `else`[^2],
but they all seemed useful. In general this seems to reduce nesting, and
also make overall flow clearer.

[^1]: https://docs.astral.sh/ruff/rules/#flake8-return-ret
[^2]: https://docs.astral.sh/ruff/rules/superfluous-else-return/

Author: bbannier

btest

@@ -263,9 +263,7 @@ def ExpandBackticks(origvalue):
 
         return out.strip()
 
-    value = reBackticks.sub(_exec, origvalue)
-
-    return value
+    return reBackticks.sub(_exec, origvalue)
 
 
 # We monkey-patch the config parser to provide an alternative method that
@@ -1488,12 +1486,11 @@ class Test:
             self.diagmsgs += [f"'{cmdline}' succeeded unexpectedly (exit code 0)"]
             return (False, 0)
 
-        else:
-            if not cmd.expect_success:
-                return (True, rc)
+        if not cmd.expect_success:
+            return (True, rc)
 
-            self.diagmsgs += [f"'{cmdline}' failed unexpectedly (exit code {rc})"]
-            return (False, rc)
+        self.diagmsgs += [f"'{cmdline}' failed unexpectedly (exit code {rc})"]
+        return (False, rc)
 
     def rmTmp(self, *, with_close=False):
         if with_close:
@@ -1553,8 +1550,8 @@ class Test:
     def timePostfix(self):
         if self.utime_base >= 0 and self.utime >= 0:
             return f" ({self.utime_perc:+.1f}%)"
-        else:
-            return ""
+
+        return ""
 
     # Picks up any progress output that has a test has written out.
     def parseProgress(self):
@@ -1612,8 +1609,8 @@ class OutputHandler:
             # requested, plus 1 for "#".
             width = len(str(self.options().threads)) + 1
             return f"[{mp.current_process().name:>{width}}]"
-        else:
-            return ""
+
+        return ""
 
     def _output(self, msg, nl=True, file=None):
         if not file:
@@ -2555,10 +2552,10 @@ def readTestFile(filename):
             t = Test(filename)
             if t.parse(content, filename):
                 return t
-            else:
-                return None
-        else:
-            return previous.clone(content)
+
+            return None
+
+        return previous.clone(content)
 
     if os.path.basename(filename) == ".btest-ignore":
         return []

pyproject.toml

@@ -73,4 +73,4 @@ per-file-ignores = """
 """
 
 [tool.ruff.lint]
-select = ["C4", "F", "I", "ISC", "UP"]
+select = ["C4", "F", "I", "ISC", "RET", "UP"]