1 files changed, 14 insertions, 0 deletions
diff --git a/coverage/files.py b/coverage/files.py
index 87a18bc2..2c520b8a 100644
--- a/coverage/files.py
+++ b/coverage/files.py
@@ -409,6 +409,20 @@ class PathAliases:
                     f"producing {new!r}"
                 )
                 return new
+
+        # If we get here, no pattern matched.
+
+        if self.relative and not isabs_anywhere(path):
+            parts = re.split(r"[/\\]", path)
+            if len(parts) > 1:
+                dir1 = parts[0]
+                pattern = f"*/{dir1}"
+                regex = rf"^(.*[\\/])?{re.escape(dir1)}[\\/]"
+                result = f"{dir1}{os.sep}"
+                self.debugfn(f"Generating rule: {pattern!r} -> {result!r} using regex {regex!r}")
+                self.aliases.append((pattern, re.compile(regex), result))
+                return self.map(path)
+
         self.debugfn(f"No rules match, path {path!r} is unchanged")
         return path