logging: Fix log formatting with colored output

The log message is already formatted before being passed to the colorer.
To avoid the exception "TypeError: not enough arguments for format
string", we should use the `nofmt_colorer` instead.

This bug occurs only when the formatted string still contains '%'
character. The following snippet can reproduce the bug:

```
from repo_logging import RepoLogger
RepoLogger(__name__).error("%s", "100% failed")
```

Change-Id: I4e3977b3d21aec4e0deb95fc1c6dd1e59272d695
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/432017
Tested-by: Shik Chen <shik@google.com>
Commit-Queue: Shik Chen <shik@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

repo_logging.py

@@ -39,8 +39,8 @@ class _LogColoring(Coloring):
 
     def __init__(self, config):
         super().__init__(config, "logs")
-        self.error = self.colorer("error", fg="red")
-        self.warning = self.colorer("warn", fg="yellow")
+        self.error = self.nofmt_colorer("error", fg="red")
+        self.warning = self.nofmt_colorer("warn", fg="yellow")
         self.levelMap = {
             "WARNING": self.warning,
             "ERROR": self.error,

tests/test_repo_logging.py

@@ -13,9 +13,14 @@
 # limitations under the License.
 
 """Unit test for repo_logging module."""
+
+import contextlib
+import io
+import logging
 import unittest
 from unittest import mock
 
+from color import SetDefaultColoring
 from error import RepoExitError
 from repo_logging import RepoLogger
 
@@ -62,3 +67,35 @@ class TestRepoLogger(unittest.TestCase):
                 mock.call("Repo command failed: %s", "RepoExitError"),
             ]
         )
+
+    def test_log_with_format_string(self):
+        """Test different log levels with format strings."""
+
+        # Set color output to "always" for consistent test results.
+        # This ensures the logger's behavior is uniform across different
+        # environments and git configurations.
+        SetDefaultColoring("always")
+
+        # Regex pattern to match optional ANSI color codes.
+        # \033    - Escape character
+        # \[      - Opening square bracket
+        # [0-9;]* - Zero or more digits or semicolons
+        # m       - Ending 'm' character
+        # ?       - Makes the entire group optional
+        opt_color = r"(\033\[[0-9;]*m)?"
+
+        for level in (logging.INFO, logging.WARN, logging.ERROR):
+            name = logging.getLevelName(level)
+
+            with self.subTest(level=level, name=name):
+                output = io.StringIO()
+
+                with contextlib.redirect_stderr(output):
+                    logger = RepoLogger(__name__)
+                    logger.log(level, "%s", "100% pass")
+
+                self.assertRegex(
+                    output.getvalue().strip(),
+                    f"^{opt_color}100% pass{opt_color}$",
+                    f"failed for level {name}",
+                )