As a workaround it can be used undocumented feature of gEDA pcb like Kai Martin Knaak stated in geda-user mailing list and which about I did not know till we discussed units conversion and mixed units:
"Yes, pcb likes to choose units on an item-to-item base
according to non-trivial rules. Fortunately, since about 2014 unit mixing
can be prevented by the directive "save-metric-only = 1" in
$HOME/.pcb/preferences . This is a non-documented feature which apparently
did not make it to the manual. Command line help "pcb -h" reveals it,
though."
Very useful.
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As a workaround it can be used undocumented feature of gEDA pcb like Kai Martin Knaak stated in geda-user mailing list and which about I did not know till we discussed units conversion and mixed units:
"Yes, pcb likes to choose units on an item-to-item base
according to non-trivial rules. Fortunately, since about 2014 unit mixing
can be prevented by the directive "save-metric-only = 1" in
$HOME/.pcb/preferences . This is a non-documented feature which apparently
did not make it to the manual. Command line help "pcb -h" reveals it,
though."
Very useful.