relax type signature for PipeBuffer to accept AbstractVector{UInt8} (#52459)

Fixes #48585

Author: vtjnash

base/iobuffer.jl

@@ -123,19 +123,20 @@ function IOBuffer(;
     return buf
 end
 
-# PipeBuffers behave like Unix Pipes. They are typically readable and writable, they act appendable, and are not seekable.
+# PipeBuffers behave somewhat more like Unix Pipes (than Files). They are typically readable and writable, they act appendable, and are not seekable.
+# However, they do not support stream notification, so for that there is the BufferStream wrapper around this.
 
 """
-    PipeBuffer(data::Vector{UInt8}=UInt8[]; maxsize::Integer = typemax(Int))
+    PipeBuffer(data::AbstractVector{UInt8}=UInt8[]; maxsize::Integer = typemax(Int))
 
 An [`IOBuffer`](@ref) that allows reading and performs writes by appending.
 Seeking and truncating are not supported.
 See [`IOBuffer`](@ref) for the available constructors.
 If `data` is given, creates a `PipeBuffer` to operate on a data vector,
 optionally specifying a size beyond which the underlying `Array` may not be grown.
 """
-PipeBuffer(data::Vector{UInt8}=UInt8[]; maxsize::Int = typemax(Int)) =
-    GenericIOBuffer(data,true,true,false,true,maxsize)
+PipeBuffer(data::AbstractVector{UInt8}=UInt8[]; maxsize::Int = typemax(Int)) =
+    GenericIOBuffer(data, true, true, false, true, maxsize)
 PipeBuffer(maxsize::Integer) = (x = PipeBuffer(StringVector(maxsize), maxsize = maxsize); x.size=0; x)
 
 _similar_data(b::GenericIOBuffer, len::Int) = similar(b.data, len)