Lockfile modified when installing from lockfile

[scassard]

I've encountered an issue while using "Install dependencies (as specified in lockfile)". Several times, my lockfile was modified after this operation.
It does not happen at each time, but I figured out a case in which it happens.

Initial state of the lockfile :

[...]
# SOLVED DEPENDENCIES
A 1.0
    B 1.0+
B1.1

Then I updated B to 1.2 version

[...]
# SOLVED DEPENDENCIES
A 1.0
    B 1.0+
B1.2

And after running "Install dependencies (as specified in lockfile)", and the lockfile is modified as followed :

[...]
# SOLVED DEPENDENCIES
A 1.0
    B 0.9+
B1.2

And 0.9+ was a transitive dependency in a previous version of my package A.