gh-149015: Fix iterate-and-delete issue in Bdb.clear_all_file_breaks

When multiple breakpoints share the same line, iterating over blist while
calling bp.deleteMe() (which mutates blist) causes alternate elements to
be skipped, leaving orphan breakpoints.

This is a one-character fix: add [:] to create a copy before iterating,
matching the existing defensive pattern in clear_break() at line 722.

Author: Godzilaa

Lib/bdb.py

@@ -747,7 +747,7 @@ def clear_all_file_breaks(self, filename):
             return 'There are no breakpoints in %s' % filename
         for line in self.breaks[filename]:
             blist = Breakpoint.bplist[filename, line]
-            for bp in blist:
+            for bp in blist[:]:
                 bp.deleteMe()
         del self.breaks[filename]
         return None