[G5K] Walltime can't go above 23:59:59

G5K provider tries to validate Walltime format using the is_valid_walltime function. The validation process does as follow:

• Verify if walltime parameter is a string -> If not, not valid
• Verify if walltime parameter is a date-time -> if not, not valid

The second point is currently implemented by verifying if it corresponds to "%H:%M:%S" format. This verification raises an issue: a walltime can be valid without being a valid time.

Example: a walltime superior than 23:59:59 (can be the case during weekend jobs).

An idea to fix this: verify if the hour, min, sec are positive or null integers, and if min and sec are <=59.

If it sounds good @msimonin, I could try to implement it.