storing wrong alternative name as local data

[DanPorter]

When evaluating a string from a nexus file using the alternative names expression, the wrong name is stored, resulting in future evaluations taking the incorrect value.

For example:

import hdfmap

f1 = '/dls/i16/data/2025/cm40634-15/1114142.nxs'
f2 = '/dls/i16/data/2025/cm40634-15/1114141.nxs'

m = hdfmap.create_nexus_map(f1)

with hdfmap.load_hdf(f1) as nxs:
    scan_command1 = m.get_data(nxs, 'scan_command')
    cmd1 = m.eval(nxs, '(cmd|scan_command)')
    path1 = m.eval(nxs, '_(cmd|scan_command)')
    print(f"Scan command1: {scan_command1}")
    print(f"         cmd1: {cmd1}")
    print(f"        path1: {path1}")
    print(f"'{path1}' in f2: {path1 in nxs}")
print(m._local_data)
with hdfmap.load_hdf(f2) as nxs:
    scan_command2 = m.get_data(nxs, 'scan_command')
    cmd2 = m.eval(nxs, '(cmd|scan_command)')
    path2 = m.eval(nxs, '_(cmd|scan_command)')
    print(f"Scan command2: {scan_command2}")
    print(f"         cmd2: {cmd2}")
    print(f"        path2: {path2}")
    print(f"'{path2}' in f2: {path2 in nxs}")

Results:

Scan command1: scan stokes_fly (0,5.0,10.0,15.0,20.0,25.0) xmapMca 10 pil3_100k 10
         cmd1: flyscan stokes 0 30 5 xmapMca 10 pil3_100k 10
        path1: /entry/user_input/cmd
'/entry/user_input/cmd' in f2: True
{'cmd': 'flyscan stokes 0 30 5 xmapMca 10 pil3_100k 10', 'filepath': '/dls/i16/data/2025/cm40634-15/1114142.nxs', 'filename': '1114142.nxs', '_cmd': '/entry/user_input/cmd'}
Scan command2: scan stokes 30 0 5 xmapMca 10 pil3_100k 10
         cmd2: flyscan stokes 0 30 5 xmapMca 10 pil3_100k 10
        path2: /entry/user_input/cmd
'/entry/user_input/cmd' in f2: False