[R] Dataframe columns are accessible by incomplete column names, is this a bug?

[Y@@@ick@Suter m@iii@g oii coop@ch]

Hello all
I noticed today that you can access dataframe columns by using incomplete names. This is a really unexpected behavior which led to some unexpected errors and I was wondering whether it's a bug or not and whether it should be changed in the future.
Here's a working example using the preinstalled "swiss" dataset:

> head(swiss)
             Fertility Agriculture Examination Education Catholic
Courtelary        80.2        17.0          15        12     9.96
Delemont          83.1        45.1           6         9    84.84
Franches-Mnt      92.5        39.7           5         5    93.40
Moutier           85.8        36.5          12         7    33.77
Neuveville        76.9        43.5          17        15     5.16
Porrentruy        76.1        35.3           9         7    90.57
             Infant.Mortality
Courtelary               22.2
Delemont                 22.2
Franches-Mnt             20.2
Moutier                  20.3
Neuveville               20.6
Porrentruy               26.6
> swiss$E
NULL
> swiss$Ex
[1] 15  6  5 12 17  9 16 14 12 16 14 21 14 19 22 18 17 26 31 19 22 14 22 20 12
[26] 14  6 16 25 15  3  7  5 12  7  9  3 13 26 29 22 35 15 25 37 16 22
> swiss$Ed
[1] 12  9  5  7 15  7  7  8  7 13  6 12  7 12  5  2  8 28 20  9 10  3 12  6  1
[26]  8  3 10 19  8  2  6  2  6  3  9  3 13 12 11 13 32  7  7 53 29 29

So in order to access the column "Examination", I can type any substring from "Ex" to "Examination" and will always get the column swiss$Examination.

Thanks for reading and Greetings
Yannick Suter

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