The threee tags `<name>`, `</name>` and `<command>` were frequently used
with a leading space that this removes. The reason this habbit is so
widespread in testcases is probably that they have been copy and pasted.
Hence, fixing them all now might curb this practice from now on.
Closes#12028
Previously it would end up with an uninitialized memory buffer that
would lead to a crash or junk getting output.
Added test 1271 to verify.
Reported-by: Brian Carpenter
Closes#4786