Unnecessary apostrophe in English base::summary() NA count output?

Hello, this is quite a minor issue but as summary() is in all likelihood
one of the most widely used functions in R I decided to email this list.
When producing a count of missing values, summary() in English generates an
unnecessary and grammatically incorrect apostrophe (NA's rather than NAs)
in its table header.  For example:

summary(c(1,2,NA,3,4,NA))

Min. 1st Qu.  Median    Mean 3rd Qu.    Max.    NA's
   1.00    1.75    2.50    2.50    3.25    4.00       2

The issue can be traced to this file:
https://svn.r-project.org/R/trunk/src/library/base/R/summary.R
Unless this is being done intentionally for some reason, the solution would
seem to be to replace the string "NA's" with "NAs".  There are 9
occurrences in the file.

Thank you very much.