gh-37912: Filter "RuntimeWarning: networkx backend defined more than …

…once for networkx"

    
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- Fixes #37863

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URL: #37912
Reported by: Matthias Köppe
Reviewer(s): David Coudert, Kwankyu Lee

src/sage/all__sagemath_repl.py

@@ -96,6 +96,11 @@
                         message=r"Pickle, copy, and deepcopy support will be "
                                 r"removed from itertools in Python 3.14.")
 
+# triggered in Python 3.9 on Redhat-based distributions
+# https://github.com/sagemath/sage/issues/37863
+# https://github.com/networkx/networkx/issues/7101
+warnings.filterwarnings('ignore', category=RuntimeWarning,
+                        message="networkx backend defined more than once: nx-loopback")
 
 from sage.all__sagemath_objects import *
 from sage.all__sagemath_environment import *