Update err for single conn pool when context.Done() return first

internal/pool/pool_single.go

@@ -37,6 +37,9 @@ func (p *SingleConnPool) Put(ctx context.Context, cn *Conn) {}
 func (p *SingleConnPool) Remove(ctx context.Context, cn *Conn, reason error) {
 	p.cn = nil
 	p.stickyErr = reason
+	if reason == nil && ctx != nil {
+		p.stickyErr = ctx.Err()
+	}
 }
 
 func (p *SingleConnPool) Close() error {

internal/pool/pool_single_test.go

@@ -0,0 +1,31 @@
+package pool_test
+
+import (
+	"context"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"github.com/go-pg/pg/v10/internal/pool"
+)
+
+var _ = Describe("SingleConnPool", func() {
+	var p *pool.SingleConnPool
+
+	BeforeEach(func() {
+		p = pool.NewSingleConnPool(nil, &pool.Conn{})
+	})
+
+	It("remove a conn due to context is cancelled", func() {
+		ctx, cl := context.WithCancel(context.TODO())
+		cn, err := p.Get(nil)
+		Expect(err).To(BeNil())
+		Expect(cn).ToNot(BeNil())
+
+		cl()
+		p.Remove(ctx, cn, nil)
+		cn, err = p.Get(nil)
+		Expect(cn).To(BeNil())
+		Expect(err).ToNot(BeNil())
+	})
+
+})