I tested the bzr-version and the size for A4 is still wrong. 

hostname:~$ ./simple-scan --version
simple-scan 1.0.0
hostname:~$ ./simple-scan --debug > ~/debug.txt

I think this is the important part of the debug log file:

** (simple-scan:23328): DEBUG:   Description: Sets the horizontal resolution of the scanned image.
** (simple-scan:23328): DEBUG: sane_control_option (4, SANE_ACTION_SET_VALUE, 150) -> (SANE_STATUS_GOOD, 150) 
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (5)
** (simple-scan:23328): DEBUG: Option 5: name='y-resolution' title='Y-resolution' type=int size=4 unit=dpi min=50, max=600, quant=1 cap=soft-select,soft-detect
** (simple-scan:23328): DEBUG:   Description: Sets the vertical resolution of the scanned image.
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (6)
** (simple-scan:23328): DEBUG: Option 6: name='geometry' title='Geometry' type=group size=4 cap=inactive
** (simple-scan:23328): DEBUG:   Description: Scan area and media size options
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (7)
** (simple-scan:23328): DEBUG: Option 7: name='tl-x' title='Top-left x' type=fixed size=4 unit=mm min=0.000000, max=215.872192, quant=1387 cap=soft-select,soft-detect
** (simple-scan:23328): DEBUG:   Description: Top-left x position of scan area.
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (8)
** (simple-scan:23328): DEBUG: Option 8: name='tl-y' title='Top-left y' type=fixed size=4 unit=mm min=0.000000, max=279.364014, quant=1387 cap=soft-select,soft-detect
** (simple-scan:23328): DEBUG:   Description: Top-left y position of scan area.
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (9)
** (simple-scan:23328): DEBUG: Option 9: name='br-x' title='Bottom-right x' type=fixed size=4 unit=mm min=0.000000, max=215.872192, quant=1387 cap=soft-select,soft-detect
** (simple-scan:23328): DEBUG:   Description: Bottom-right x position of scan area.
** (simple-scan:23328): DEBUG: sane_control_option (9, SANE_ACTION_SET_VALUE, 215.872192) -> (SANE_STATUS_GOOD, 215.872192)
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (10) 
** (simple-scan:23328): DEBUG: Option 10: name='br-y' title='Bottom-right y' type=fixed size=4 unit=mm min=0.000000, max=279.364014, quant=1387 cap=soft-select,soft-detect
** (simple-scan:23328): DEBUG:   Description: Bottom-right y position of scan area.
** (simple-scan:23328): DEBUG: sane_control_option (10, SANE_ACTION_SET_VALUE, 279.364014) -> (SANE_STATUS_GOOD, 279.364014)
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (11) 
** (simple-scan:23328): DEBUG: Option 11: name='page-width' title='Page width' type=fixed size=4 unit=mm min=0.000000, max=221.120850, quant=1387 cap=soft-select,soft-detect
** (simple-scan:23328): DEBUG:   Description: Specifies the width of the media.  Required for automatic centering of sheet-fed scans.
** (simple-scan:23328): DEBUG: sane_control_option (11, SANE_ACTION_SET_VALUE, 210.009781) -> (SANE_STATUS_GOOD, 210.000000)
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (12)
** (simple-scan:23328): DEBUG: Option 12: name='page-height' title='Page height' type=fixed size=4 unit=mm min=0.000000, max=876.695068, quant=1387 cap=soft-select,soft-detect
** (simple-scan:23328): DEBUG:   Description: Specifies the height of the media.
** (simple-scan:23328): DEBUG: sane_control_option (12, SANE_ACTION_SET_VALUE, 296.993576) -> (SANE_STATUS_GOOD, 297.000000)
** (simple-scan:23328): DEBUG: sane_get_option_descriptor (13)
** (simple-scan:23328): DEBUG: Option 13: name='enhancement' title='Enhancement' type=group size=4 cap=inactive