Fix issue where bootstrap incorrectly determines git branch if starti…

…ng bootstrap outside Spyder repo.

bootstrap.py

@@ -86,7 +86,7 @@
         prev_branch = boot_branch_file.read_text()
 
     result = subprocess.run(
-        ["git", "merge-base", "--fork-point", "master"],
+        ["git", "-C", DEVPATH, "merge-base", "--fork-point", "master"],
         capture_output=True
     )
     branch = "master" if result.stdout else "not master"