creating subgraph does not delete _pos entries

[jasongrout]

This means that later, a call to relabel fails. This affects, for example, the graph isomorphism code (which was how the error was originally found).

Component: graph theory

Issue created by migration from https://trac.sagemath.org/ticket/3055

[jasongrout]

comment:1

Attachment: trac-3055-subgraph-del-pos.patch.gz

With #3054 and #3055 applied, doctests pass in the graphs/ directory.

[rlmill]

comment:2

Have not run doctests, but I support this fix.

[sagetrac-mabshoff]

comment:3

#3054 and #3055 applied to my current merge tree doctest clean. So I am considering this a positive review.

Cheers,

Michael

[sagetrac-mabshoff]

comment:4

Merged in Sage 3.0.1.alpha1

[jasongrout]

comment:5

Tracy McKay and Laura DeLoss should also get credit for exposing this bug.

[sagetrac-mabshoff]

comment:6

Replying to @jasongrout:

Tracy McKay and Laura DeLoss should also get credit for exposing this bug.

Well, did they fix the bug? So far we only give credit for doing that. People who find bugs are not credited and while we could add a "reported by FOO" byline I am not sure those people will get added to the credit list.

Cheers,

Michael